The main malfunctions of the power supply system of the gasoline engine. Car engine power system repair. In addition to all of the above, the engine itself plays an important role, or rather its technical condition

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When troubleshooting a carburetor, it is very important to immediately exclude the possibility of a malfunction in the fuel supply system of the carburetor. And also in the ignition system. In other words, it is necessary to take any intervention in the carburetor last, after making sure that other systems are working.

Various disturbances in the operation of the carburetor most often manifest themselves in a deterioration in the driving performance of the car. Driving performance should be understood as a set of factors that determine the driver's sensations when acting on the throttle pedal and which he subjectively associates with the acceleration of the car.

The human body is very sensitive to acceleration and reacts to small changes in it. Violations of normal driving characteristics, presumably resulting from a defect in the carburetor, can be said if the expected habitual change in movement does not occur when the throttle position is changed, i.e.

acceleration.

note

The nature of the violation of normal driving characteristics can very accurately indicate the cause of the malfunction. It is useful for the owner of an individual car to know about the main types of these violations, known by names: failure, jerking, twitching, swaying, sluggish acceleration.

Failure is a well-perceived, rather long (from 0.5 to 5 s and more) decrease in acceleration up to the transition to deceleration, despite the opening throttle valves... The degree of its manifestation is characterized by the term “depth” by analogy with a hole, a hole in the road.

A dash is, in fact, the same failure, but more limited in time (0.1 ... 0.4 s).

A twitch is a series of light, short jerks following one after another.

Swinging is a series of successive failures.

Sluggish acceleration is understood as a low rate of increase in vehicle speed.

The main malfunctions of the carburetor are wear of the shut-off needle valve, dents and cracks on the float, wear of the calibrated holes of the nozzles and the needle of the main nozzle, violation of the adjustment of the maximum engine speed limiter.

After disassembly, washing in kerosene and blowing with compressed air, the carburetor parts are inspected, measured and checked on instruments and devices. The nozzles are checked for throughput.

If it is more than stipulated technical conditions, the jet is worn out and must be replaced. The diffuser plates must also be replaced if their elasticity is below the permissible specifications.

The needle check valve is restored by lapping.

Cracks in the float are sealed with soft solder. Before soldering, the gasoline that has got inside the float is evaporated. To do this, it is placed in hot water and kept in it for several minutes. At the same time, the place of damage is determined by the emerging bubbles. After soldering, check the mass of the float, which must meet the requirements of the technical specifications.

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Vaz 2109: carburetor malfunctions and what happens at the same time

Carburetor vaz

When the carburetor does not work smoothly on a VAZ 2109, the engine does not suffer, its power drops, noise appears, pops, rattling, parts of the connecting rod mechanism go into gear.

Half of these problems can be corrected by an elementary carburetor adjustment, however, in case of breakdowns that occur more often with a car with a solid mileage, the adjustment does not solve the problem.

The main thing is not to rush and figure out when the carburetor does not work on the VAZ 2109, whether it is caused by a breakdown or still a lack of adjustment.

Basics of the device and principle of operation

The carburetor serves to prepare a proportional mixture of gasoline and air from atmospheric air and from the fuel supplied from the tank, in accordance with the engine operating modes, and then supply this mixture to the cylinders.
But everything is not as simple as it seems at first:

• Despite its small size, it is one of the most complex units in the power supply system.
• Even if motorists decide to repair it with their own hands, then, as a rule, most of them do not penetrate beyond the float chamber.
• Although, the cause of the malfunction according to the law of meanness is often hidden much deeper
• Then the question arises - whether to repair the carburetor (see Repairing a VAZ 2109 carburetor at home) or not to mess around and buy a new one
• You can buy if the price suits you, or go to a service station, where repairs can cost half the cost
• The most economical way to repair yourself

Let's look at the carburetor from all sides to make it clearer where its components are located, see the photo:

Left view

Right view

Component details

Any carburetor contains:

• float chamber
• mixing chamber
• needle valve float
• spray
• channels for fuel and air with jets
• diffuser
• air and throttle dampers

Float chamber operation

Now it's time to consider how the float chamber works:

• The required level of gasoline in the float chamber is maintained by a float that is connected to a needle valve
• As fuel is consumed, the float descends, thus releasing the needle valve, and a portion of gasoline is poured into the fuel chamber
• When the chamber reaches required level fuel, then the float rises, pressing the valve and thereby closing the access of gasoline through the inlet
• Passing through the atomizer tube on the way from the float chamber, the fuel enters the mixing chamber, where it mixes with the air coming from the inlet pipe
• To prevent gasoline from spilling out of the float chamber, if the car is standing, not on a level platform, but on a slope, the fuel level in it is adjusted below the level of the outlet

How it works in general

The next question is also important, how the carburetor works in general:

• The diffuser is used to inject the air flow rate into the mixing chamber.
• It also creates a vacuum at the end of the atomizer when the engine is in operation.
• Vacuum is necessary to pump gasoline out of the float chamber and improve atomization
• The saturation of the combustible mixture, which is supplied to the engine cylinders, is controlled by the throttle valve, which is connected by a cable to the gas pedal
• The damper changes the cross-sectional area of ​​the air passage and, accordingly, the air flow into the mixing chamber
• By closing the damper, we reduce the air flow and enrich the gasoline-air mixture, opening it, we supply more air, according to the engine operating mode, which are regulated by the degree of pressing the gas pedal by the driver
• In addition, under the dashboard, or on it there is a special knob that controls the carburetor flap (the knob is called by drivers: "suction")
• By pulling on it, the driver closes the air damper, thereby limiting the air flow and increases the vacuum inside the mixing chamber.
• Then gasoline begins to be sucked out of the float chamber more intensively, and a saturated combustible mixture is obtained from a lack of air, which is exactly what is needed to start a cold engine
• From this, a simple and understandable conclusion is obtained - the carburetor will work most economically at medium loads.
• And the movement in jerks will accordingly increase the consumption of gasoline, because a sharp press on the gas requires a more saturated mixture for the engine
• When you have the time and desire to clean the carburetor yourself, then basic knowledge about its structure will certainly come in handy.
• Many malfunctions of the carburetor can be eliminated without removing it from the car.
• In doing so, however, you will need to maintain cleanliness, which can be difficult to ensure inside. engine compartment car
• Plus, most of the parts are small, so it's easy to drop them and even lose them.
• Therefore, even for minor repairs, it is recommended to remove it from the engine.
• And during the repair process directly on the engine, you should exclude any possibility of foreign objects and dirt getting inside the carburetor
• It is advisable to first wash the initially dirty carburetor from the outside.

When the carburetor jumps on a VAZ 2109, the engine stalls at idle, this is because:

• It has an excessively high or low level, as well as a complete absence of fuel in the float chamber
• The air damper does not open to the end, even when the handle of its drive is completely drowned, therefore, the carburetor does not hold idle on the VAZ 2109
• Air leaks through damage in the drain pipe
• Violation of the tightness of the diaphragm of its starting device
• In the carburetor, the condensate of the VAZ 2109 donkey and water turned out

Lean mix

Too lean mixture is created:

• Due to improper adjustment of the carburetor
• Clogging of the fuel jet designed for idle speed or the channel of the idle speed system
• Broken fuel cut-off valve
• Lost tightness of the system due to damage to the base of the carburetor, or the manifold gasket, or vacuum hoses. Probably, VUT is faulty.
• Punched gasket under the top cover
• The carburetor body or the throttle valve axle is worn out, therefore the valves are jammed
• Malfunction or poor adjustment of the throttle actuator
• Weakening or absence of a plug of fuel or air passages
• Damage to the idle jet socket
• Spoiled screw for adjusting the quality of the mixture

Fortified mixture

What causes the excessive enrichment of the mixture:

• From improper carburetor adjustment
• Clogged air jet
• The weakening of the fuel jet standing on idling or an idle solenoid (it may not be there)
• Depressurization of the float
• Needle valve malfunction
• Choke stuck fully open
• Heavy carbon deposits have formed around the throttle plate
• The required amount of opening of the throttle valve does not correspond
• Incorrectly installed throttle plate in the secondary chamber
• Damaged top cover gasket
• The system serving for forced ventilation crankcase
• Malfunction of the ignition system

Exceeding normal speed XX

When the idle speed is too high:

• This means that the quality screw installed in the idle system is incorrectly adjusted.
• Wear on the throttle valve shaft or axle holes located in the carburetor body (and when the speed drops to idle, so the speed may not return to its original value)
• Air damper sticking in working (closed) position
• It is possible that the rods are stuck or improperly adjusted, or the throttle actuator levers
• The throttle valve in the secondary chamber is open to an amount that is unacceptable at idle

Walking turnovers XX

The XX revolutions smoothly increase, and then also smoothly decrease (in a cyclic mode):

• This comes from improper adjustment of the contacts of the economizer micro switch regulating forced idle (EPCH)

Difficulty starting the engine

Difficulty starting a cold engine:

• The fuel filter is clogged in the carburetor
• The needle valve gets stuck (this is the wrong level or lack of fuel in the float chamber)
• The air damper does not close completely.
• Idle solenoid valve malfunction
• Defective operation of the EPHH unit, an open in the electrical circuit, the carburetor has no mass on the VAZ 2109
• When the air damper is fully closed, the throttle in the primary chamber does not open slightly
• Fault in the starting device. In this case, the air damper remains closed when the first flashes occur in the cylinders.
• Violation of the tightness of the pneumatic line
• Sucks in air through a loose fit of the carburetor body connectors or the flange of its attachment to the engine intake manifold
• Fuel leaks
• Malfunction fuel pump
• Ignition system malfunction Difficulty starting a hot engine:
• If the level of fuel in the float chamber is incorrect
• Needle valve leaks
• The float is depressurized
• The axle of the float is worn out. The float may be stuck
• The ventilation of the float chamber is clogged
• Excessive depletion or enrichment of the idle mixture occurs
• It is possible that some kind of malfunction from the previous paragraph

Air damper problems

Air damper malfunction:

• Air damper stuck open
• Broken air damper rod
• Incorrect adjustment or malfunction of the air damper opening system
• Incorrect adjustment or malfunction of the starting device

Motor stalls

The motor stops when it is forced to idle:

• Clogging or open circuit of the EPHH electrical circuit

Increased fuel consumption

Possible reasons for an increase in gas mileage:

• Possible one of the reasons that are already listed in the paragraph "Difficulty starting a hot engine"
• Air damper not fully open
• Clogging air jets
• Too high speed XX
• Malfunction unit EPHH
• Gasoline leak
• In a vaz 2109, the carburetor overflows
• Clogged air filter
• Malfunction of elements of the ignition system

Shoots the carburetor

Flashbacks (shots) or loud popping (from inlet).
On a VAZ 2109, pops in the carburetor occur for the following reasons:

• Intake manifold vacuum leaks
• The needle valve is stuck or the fuel line is clogged
• Highly lean working mixture
• Burned inlet valve
• The ignition moment is incorrectly set, shoots the carburetor on the VAZ 2109

The engine starts but it jams

Malfunctions in the engine after turning on the ignition:

• The appearance of malfunctions in the idle economizer system (aka EPHH), such as: poor contact, open circuit in the electrical circuit; breakage / poor adjustment of the microswitch; malfunctions in electronic unit management
• Defective solenoid valve
• Check valve needle worn out
• Overheating of the motor

Loss of motor power

The engine has lost power, there are interruptions in its operation:

• The throttle valves do not open completely
• The throttle valves of the primary or secondary chamber are stuck
• Reduced level of gasoline in the float chamber
• Too lean or too rich idle mixture
• Idle fuel cut-off valve malfunction. The carburetor is poured onto the vaz 2109
• Clogged jets or internal fuel line
• Weakening of air or fuel jets
• Econostat channel clogged
• Plugged or blocked orifice in the secondary chamber transition system (this can cause transient interruptions when the secondary chamber throttle starts to open)
• When the engine only runs on the secondary chamber (i.e. with the throttle valve fully open), the main fuel jet in the primary chamber is likely clogged.
• Incomplete opening of the air damper when the handle of its drive is drowned
• Accelerator pump malfunction: diaphragm damage; clogged channel or pump spray
• Dirty air filter

Lean Mix in Motion

Extremely lean mixture while driving:

• When the idle mixture is correct and there are no obvious carburetor malfunctions, the overall mixture may well be lean. We check the CO concentration at the engine speed of 3000 rpm.
• The concentration must be at least 50% compared to the no-load concentration
• Defective fuel pump or clogged fuel filters
• Malfunctions in the ignition system

If the engine overheats

Perhaps excessive depletion of the combustible mixture, which is caused by:

• Low fuel float chamber
• Littering of the main fuel jets
• Suction of air through the appeared non-densities in the carburetor connectors or the flange of the attachment to the intake manifold

Excessive enrichment of the mixture, caused by:

• Inflated level of gasoline in the float chamber
• Dirty main air jets
• Detonation shocks when the engine is running under load
• Excessive depletion of the mixture, the VAZ 2109 carburetor jerks when driving and under load
• Intermittently appearing and then disappearing interruptions in the operation of the motor
• Entry of foreign particles into the channels of the idle system
• The appearance of foreign particles in the fuel channels, or the float chamber, which overlap the nozzles

Motor stalls

If the engine stalls immediately after starting:

• The additional resistance of the ignition coil may have burned out (of course, if there is one)

There is a separate instruction to eliminate each malfunction. Our article helps to understand the possible reason not to overpay the repairmen for some reason, and not to buy a new carburetor if it has nothing to do with it!
As for the video, here, too, choose based on the identified problem.

Solex carburetor

When operating a car, some malfunctions of the carburetor can be identified by characteristic signs in the form of certain irregularities in the operation of the engine and the car.
The main violations are difficult starting of the engine, interruptions in operation, which in turn cause failure, jerk, twitching, swaying and sluggish acceleration of the car, as well as an increase in operating fuel consumption.

The listed malfunctions of the engine and the car can be caused not only by the failure of the systems and components of the carburetor, but also by the malfunction of other systems of the car, primarily ignition and fuel supply.

Ignition misfires in the engine cylinders, leading to interruptions in its operation, are associated with a violation of the gaps between the spark plug electrodes and the contacts of the interrupter-distributor.

The same phenomena occur due to improper installation of the initial ignition moment, mechanical wear, damage to parts and violation of the integrity of the distributor insulation, wires and high voltage terminals.

Clogging of the grid of the fuel receiver in the tank, full-flow fuel filter or carburetor filter, internal channel of the fuel line or crushing of its pipes, a decrease in the flow of the fuel pump lead to a decrease in the fuel level in the float chamber at high loads and, accordingly, to interruptions in the operation of the engine in these modes, while at idle and medium loads, the fuel level is sufficient for normal engine operation.

Difficult start a cold engine or the impossibility of starting may be the result of a malfunction of the starting device, which is expressed in incomplete closing of the air damper, which leads to a depletion of the combustible mixture, while at start it must be over-enriched.

Incomplete closing can be caused primarily by incorrect adjustment of the damper actuator.

But since the air damper in Solex carburetors is closed not by the driver directly with the help of the actuator, but by a special recoil spring, one of the reasons for incomplete closure may be a jamming of the damper in the carburetor neck when it is inaccurately installed.

If the return spring breaks or disconnects, the air damper is forcibly closed by the edge of the control lever, otherwise the starting device will not be able to open it slightly at the start of engine operation. And then the possibility of starting the engine remains, but it will be much more difficult due to the deterioration of the mixture formation conditions.

In carburetors with a semi-automatic starting device, incomplete closing of the air damper can occur due to damage to the bimetallic spring or its incorrect installation.

At the same time, if the air damper closes normally, and the diaphragm mechanism of the starting device is faulty, it does not slightly open the air damper with the first flashes in the cylinders and the engine will stop immediately after starting, since the over-enriched combustible mixture “floods” the spark plugs.

It should be noted that even with a fully functional starting device, starting a cold engine will be difficult if the starting clearances of the air and throttle valves are not adjusted.

Starting a warm engine is significantly difficult or even impossible when the combustible mixture is re-enriched due to an excessively high fuel level in the float chamber and malfunctions in the EPHH and electronic control mixture ratio (if present): solenoid valves do not open the idle and main metering system fuel jets. In the first case, it is possible to start the engine only after "purging" its cylinders, turning crankshaft starter with fully open throttle valves. In the second case, the engine, started when the accelerator pedal is fully depressed, will immediately stop when it is released.

Precarious work A warmed-up engine at idle speed is caused by both over-depletion and over-enrichment of the combustible mixture due to a violation of the idle speed system or clogging of the metering elements and channels, as well as an incorrect setting of the fuel level in the float chamber. The unstable operation of the engine with a serviceable idle system and the float mechanism is also caused by malfunctions of the elements of the EPHH systems (sensor-screw, solenoid valve, control unit) and electronic control of the mixture composition (actuators, sensors, thermal valve, control unit).

Interruptions in engine operation at partial and full loads and, as a consequence of this, twitching of the car in the form of a series of light short jerks following one after the other, indicate malfunctions in the operation of the main dosing systems due to contamination of their dosing elements and channels or leaks of additional air in the joints of the body parts of the carburetor due to damage to the gaskets or warpage of the mating surfaces. Disturbances in engine operation in these modes can also be caused by an excessively low fuel level in the float chamber, in which the combustible mixture is depleted at a high vacuum in the main air passages of the carburetor, and the econostat does not come into operation in a timely manner.

Failures(continuous, up to 5 s, decrease in acceleration up to deceleration) and jerks (the same dips, but lasting no more than 0.5 s) of the car during vigorous acceleration with a sharp opening of the throttle valves are caused by malfunctions of the accelerating pump (damage to the diaphragm, jamming of the drive lever, clogging of valves and nozzles, etc.) or a low fuel level in the float chamber, which reduces the pump flow.

If the idle fuel jet is clogged, a dip may occur even when the throttle valve is opened smoothly. At the same time, the engine idling is extremely unstable.

During normal idle operation, failure could be caused by improper fuel level adjustments or clogged main fuel jets.

An attempt to open the throttle valves in the event of a failure due to clogged nozzles may result in a complete stop of the engine. The same happens if the small diffusers are incorrectly installed after the complete disassembly of the carburetor, for example, for flushing it.

Rocking the car(a series of deep dips) after a short time of engine operation with fully open throttle valves, which stops after they are partially closed, caused by a fuel supply failure.

If the fuel pump is in good working order and the fuel line is clean, the cause of wobbling is a clogged fuel filter in the carburetor or a stuck needle. fuel valve in the closed position.

Insufficient engine power and its low throttle response are caused by incomplete opening of the throttle valves as a result of a malfunction of the drive as a whole or the mechanism for blocking the throttle valve of the secondary chamber. The same is observed with a decrease in the fuel level in the float chamber, a decrease in the spring elasticity of the diaphragm of the power mode economizer and clogging of its fuel jet.

Increased fuel consumption It is caused by a complex of the listed malfunctions in various combinations and is observed with incorrect adjustment of the starting device, increased fuel level, clogged air nozzles, malfunctions of the EPCH system and the economizer of power modes, when fuel leaks from under the plug of the fuel filter or fuel supply hose.

From the foregoing it follows that most of the carburetor malfunctions, and hence the engine, are associated with over-enrichment or over-depletion of the combustible mixture.

Additional external (albeit somewhat subjective) signs of mixture depletion are pops in the carburetor when starting the engine and its overheating due to the slow combustion of such a mixture throughout almost the entire operating cycle.

Due to the strong overheating of the surfaces of the combustion chamber and the electrodes of the spark plugs, poorly cooled by the depleted mixture, its spontaneous combustion is possible at a time different from the initial moment of the ignition installation, and a process similar to the detonation process in the engine cylinders, which, in addition to a drop in power, can lead to emergency damage engine.

When the fuel mixture is re-enriched, pops appear in the muffler when the accelerator pedal is suddenly released after the engine is running at a high crankshaft speed and in engine braking mode. As in the case of over-depletion of the mixture, the engine overheats greatly due to the afterburning in the exhaust pipe of the mixture unburned during the working cycle.

Engine malfunctions caused by corresponding carburetor malfunctions and methods for their elimination are summarized in tab. 3.

Methods of checking and making the carburetor systems operational are described in detail in Section 4 "Maintenance and Adjustment of the Carburetor".

The main malfunctions in the power supply system of a gasoline engine with a carburetor and their causes | Internet magazine of the motorist

The power system must ensure the preparation of a combustible mixture of the required composition (ratio of gasoline and air) and quantity, depending on the operating mode of the engine. The technical state of the power supply system determines such engine performance indicators as power, throttle response, efficiency, ease of start-up, durability.

Using gasoline of a lower quality can lead to abnormal engine operation (carbon deposits, detonation, excessive fuel consumption, burnout of cylinder head gaskets, valve heads, etc.)

). The air filters must be in good technical condition. Violation of the tightness of the case air filter and the integrity of the filter elements leads to increased passage of abrasive particles.

Power system maintenance consists in the timely check of the tightness and fastening of the fuel lines, the pipelines for the inlet of the combustible mixture and the release of exhaust gases, the action of the rods of the drives of the throttle and air valves of the carburetor, in checking the operation of the limiter of the maximum crankshaft speed once a year (in the fall), in cleaning and flushing the fuel and air filters, in disassembling, flushing and adjusting the carburetor twice a year (in spring and autumn).

Insufficient and untimely maintenance of the power supply system devices, pipelines, fuel and air supply control drives can lead to fuel leakage, the risk of fire, disruption of fuel supply, over-enrichment and over-depletion of the combustible mixture, over-consumption of fuel, malfunction of the engine, loss of power and throttle response, difficult starting and unstable engine idling. Before proceeding with the removal and disassembly of the carburetor or gasoline pump, you must make sure that the cause of the deterioration in the car's performance is not defects in other components and systems, especially the electrical system.

The technical condition of instruments and devices of the power supply system of carburetor engines is checked both when the engine is not running or when the engine is running.

With the engine off, check:

• the amount of fuel in the tank;
• condition of the gaskets under the filler plug fuel tank;
• fastening the fuel tank, fuel lines, fittings and tees;
• tightness of connections and fastening of the filter-sump, fuel pump, carburetor, air filter, inlet and outlet pipes and muffler.

With the engine running, check:

• no fuel leaks at the joints of the fuel lines, fuel tank and carburetor;
• the condition of the gaskets under the cover of the carburetor float chamber, inlet and outlet pipelines;
• settling filter;
• filter fine cleaning.

Malfunctions in the power supply system in most cases lead to the formation of a lean or rich mixture. In addition to the listed inspection and control works, the devices of the power supply system of carburetor engines are periodically checked and adjusted.

TO fuel system include a fuel tank, fuel lines, a fuel pump, a fine fuel filter, sensors, and a carburetor. Operating principle carburetor system nutrition is as follows (Figure 1).

Figure 1: Schematic diagram of the carburetor power system

When the crankshaft rotates, the fuel pump begins to operate, which sucks gasoline from the tank through a mesh filter and pumps it into the carburetor's float chamber. Before or after the pump, gasoline passes through a fine fuel filter.

note

When the piston moves down in the cylinder, fuel flows out of the atomizer of the float chamber, and purified air is sucked in through the air filter. In the mixing chamber, the air stream mixes with the fuel to form a combustible mixture. The intake valve opens, and the combustible mixture enters the cylinder, where it burns out at a certain stroke.

After that, the exhaust valve opens, and the combustion products are piped into the muffler, and from there they are discharged into the atmosphere.

The main malfunction of the power system gasoline engine with a carburetor is an increase in fuel consumption (rich mixture, increased content of CO and CH in the exhaust gases). Main reasons:

• increasing the throughput of fuel jets;
• decrease in the throughput of air jets;
• economizer valve stuck, loosely closed, prematurely opened;
• dirty air filter;
• the air damper does not open completely;
• an increase in the fuel level in the float chamber.

Depletion of the combustible mixture, reduced content of CO and CH in the exhaust gases. Main reasons:

• reduction of the fuel level in the float chamber;
• sticking of the needle valve of the float chamber in the upper position;
• contamination of fuel jets;
• weak pressure developed by the fuel pump.

The engine does not run at minimum idle speed. Main reasons:

• violation of the adjustment of the idling system of the carburetor;
• clogging of the nozzles of the idle system;
• violation of the fuel level in the float chamber;
• air leaks into the carburetor;
• air leaks into the hose vacuum booster;
• throttle bodies do not return to initial position when the control pedal is in the home position;
• malfunction of the forced idle economizer;
• water entering the carburetor.

The engine does not increase the speed, "shots" in the carburetor. Main reasons:

• poor fuel supply to the float chamber;
• clogging of jets and nozzles;
• the economizer valve does not open or is clogged;
• air leaks through leaks in the carburetor and intake manifold.

An increase in the content of CO and CH in the exhaust gases in the mode of the minimum crankshaft speed. The main reasons are:

• incorrect adjustment of the idle system;
• clogging of channels and air jets of the idle system;
• increase in the throughput of the idle fuel jets.

Fuel cut off. The main reasons are:

• clogged filters;
• damage to the valves or diaphragm of the fuel pump;
• freezing of water in the fuel lines (Fig. 2).

Solex carburetor malfunctions

The presence of possible failures in the operation of the car's power supply system can be judged by the characteristic signs of the vehicle's behavior on the road:

• Failure - in the process of pressing the gas pedal, the car for a short period of time (from 1 to 30 seconds) continues to move at the gained speed (or with deceleration), and only after a while begins to pick up speed;
• Dash - resembles a failure, but it is more short-lived;
• Wobble - periodic dips;
• A twitch is a series of jerks that follow each other;
• Sluggish acceleration is the reduced rate of increase in vehicle speed.

In addition, you can judge about the presence of malfunctions in the engine power system by the following signs:

• Increased fuel consumption;
• Engine start does not work;
• Reduced or increased idle speed;
• Difficulty starting a hot / cold engine;
• Difficult operation of the car engine in cold running mode.

Displacement of the phases of gas distribution, wear of the cams camshaft, improper adjustment of heat gaps, reduced or uneven compression in the cylinders, as well as burnout of the valves, significantly reduce the power of the car, cause vibration and increase fuel consumption.

The carburetor and its malfunctions also play an important role. Let's consider the most common carburetor malfunctions using Solex as an example. How to properly clean, check and adjust the carburetor, using the example of the VAZ 2109, is described in the article. So.

If the cylinder-piston group is worn out, then crankcase gases, oil vapors and resinous substances can get into the carburetor area, clog the filter element of the filter, and also settle on the jets and other elements of the carburetor, thereby disrupting the operation of the engine.

Typical carburetor malfunctions

If the engine does not start or stalls immediately after starting._ Perhaps this is due to the fact that there is no fuel in the float chamber or the composition of the mixture is disturbed (for example, the mixture is too rich or vice versa).

The engine idling is unstable or stalls regularly

• Clogged channels or idle jets;
• Malfunctions of the solenoid valve;
• Malfunctions of the elements of the EPHH and the control unit;
• Malfunctions and deformation of the rubber sealing ring - the "quality" screw.

Since the transitional system of the first chamber interacts with the cold running system, at incomplete revolutions, a failure, and sometimes a complete stop of the engine, is possible during the smooth start of the car. By flushing or purging the channels, the blockage can be removed, but it will need to be partially disassembled. It is also necessary to replace defective parts.

High idle speed

Reduced / increased idle speed_ can cause:

• Faulty idle adjustment:
• Reduced / increased fuel level in the chamber;
• Clogged air or fuel jets;
• Oxygen leaks into the intake manifold or carburetor through connecting hoses or at the joints;
• Partial opening of the air damper.

Difficulty starting the engine and fuel consumption

Difficulty starting a cold engine_ may cause incorrect adjustment of the starting mechanism. Partial closure of the air damper can cause a lean mixture, which in turn will cause the absence of flashes in the cylinders, and incorrectly opening it after starting the engine enriches the mixture a lot, so the engine "chokes".

Difficulty starting the car with a warm engine_ can be caused by the fact that a rich mixture enters the cylinders due to the high level of fuel that is in the float chamber. The reason for this may be a maladjustment of the fuel chamber or the fuel valve is not tight enough.

Excessive fuel consumption._ It is most difficult to eliminate this "defect", as it can be caused by various reasons.

Initially, it is worth making sure that there is no increased resistance to the movement of the vehicle, which is facilitated by the braking of the pads on drums or discs, violation of wheel mounting angles, deterioration of aerodynamic data when transporting oversized cargo on the roof or loading the car. Driving style also plays an important role.

TO great expense fuel can lead to a violation of the functionality of the carburetor:

• Malfunction of the EPHH system;
• Clogged air jets;
• Leaky closing of the solenoid valve (fuel leakage between the channel walls and the nozzle);
• Incomplete opening of the air damper;
• Economizer defects.

A deep dip before the engine stops completely with one chamber open throttle can be triggered by a clogged main fuel jet.

If the car's engine is idling or under non-significant loads, then the fuel consumption of the engine is quite low.

Trying to enter the full load mode, the fuel mass consumption increases sharply, there is not enough passability for the fuel jets, which are clogged, and dips occur in the engine's operation.

The car jerks during movement_, as well as sluggish acceleration with a "smooth" pressing of the "gas" often provokes a low fuel level if the float system is incorrectly adjusted.

Rocking, dips and jerks of the car are common phenomena at increased loads, which disappear when changing to cold running.

As a rule, they are associated with interruptions in the fuel supply system, as well as the following factors:

• The fuel pump valves are leaking;
• The fuel intake and carburetor strainers are clogged;

Dips with a sharp pressing of the "gas" _, which disappear when the car engine is running for five seconds, in the same mode can be caused by a malfunction of the accelerator pump.

Diagnostics of malfunctions of the VAZ carburetor

A malfunction of the power supply system can be diagnosed by certain signs and the characteristic behavior of the car on the road. VAZ carburetors, which will be discussed in this material, are no exception.

Signs of a malfunction of the VAZ carburetor

Signs of a malfunctioning power system

In addition to all of the above, the engine itself plays an important role, or rather its technical condition

All of these can also cause loss of power and fuel waste, and cause symptoms similar to carburetor malfunction, so before disassembling the carburetor, make sure that it is the case.

Worn parts piston group, as well as oil vapors and gases, can cause clogging of the air filter element, as well as settle on the jets and working parts of the carburetor, interfering with its normal operation.

Other symptoms also happen when the engine does not start at all or starts up, but immediately stalls.

In such cases, first of all, the reason may be caused by a lack or complete absence of fuel in the float chamber, in addition, the engine may not be started due to a too rich or too lean mixture.

Checking the fuel level in the float chamber

Typical malfunctions of K-151 carburetors of UAZ cars with UMZ-417 and UMZ-421 engines

When operating UAZ vehicles with UMZ-417 and UMZ-421 engines, some malfunctions of K-151 carburetors can be identified by characteristic signs in the form of certain malfunctions in the operation of the engine or the car as a whole.

The main irregularities in the operation of the engine are its difficult start and interruptions in operation, which in turn cause failures, jerks, jerking, swaying and sluggish acceleration of the car, as well as an increase in operating fuel consumption.

The listed violations of work engine UMP and the car can be caused not only by the failure of the systems and assemblies of the K-151 carburetors, but also by the malfunction of other systems of the car, primarily the ignition system and the fuel supply system. Therefore, before interfering with the carburetor, it is necessary to make sure that the ignition and fuel supply systems are in good working order and that the malfunctions in the engine are associated with the carburetor.

Malfunctions of the ignition system of UAZ vehicles with engines UMZ-417 and UMZ-421

Ignition misfires in the engine cylinders, leading to interruptions in its operation, are associated with a violation of the gaps between the electrodes of the spark plugs or between the contacts of the interrupter-distributor, if the car is equipped with a classic contact system ignition.

The same phenomena occur due to improper installation of the initial ignition moment, mechanical wear, damage to parts and violation of the integrity of the insulation of the distributor, high voltage wires and their tips.

Malfunctions of the fuel supply system for UAZ vehicles with UMZ-417 and UMZ-421 engines

Clogging of the grid of the fuel receiver in the tank, full-flow fuel filter or carburetor filter, internal channel of the fuel line or crushing of its pipes, a decrease in the flow of the fuel pump lead to a decrease in the fuel level in the float chamber of the carburetor at high loads and, accordingly, to interruptions in the operation of the engine in these modes, in while at idle and medium loads, the fuel level will be sufficient for normal engine operation.

Malfunctions of the starting device of the K-151 carburetors

Difficulty starting a cold engine or the inability to start may be the result of a malfunction of the starting device, which is expressed in incomplete closing of the air damper, which leads to a depletion of the air-fuel mixture, while at start it should be over-enriched. Incomplete closure of the air damper can be caused primarily by improper adjustment of its control drive. Another reason for incomplete closure may be a choke sticking due to inaccurate installation in the neck of the carburetor.

At the same time, if the air damper closes normally, and the diaphragm mechanism of the starting device is faulty, it does not slightly open the air damper with the first flashes in the cylinders and the engine will stop immediately after starting, since the over-enriched combustible mixture floods the spark plugs. At the same time, even with a fully functional starting device, starting a cold engine will be difficult if the starting clearances of the air and throttle valves are not adjusted.

Malfunctions of K-151 carburetors due to the fuel level in the float chamber or autonomous idle system

Starting a warm engine can be significantly difficult or even impossible when the air-fuel mixture is enriched due to an excessively high fuel level in the float chamber, as well as malfunctions in the autonomous idle system or forced idle economizer.

In the first case, it is possible to start the engine only after blowing out its cylinders, turning the crankshaft with a starter with fully open throttle valves. In the second case, the engine, started when the accelerator pedal is fully depressed, stops immediately when it is released.

Unstable operation of a warmed-up engine at idle speed is caused by both over-depletion and over-enrichment of the working mixture due to a violation of the idle speed system adjustment or clogging of its metering elements and channels, as well as incorrect setting of the fuel level in the float chamber.

Diagnostics of malfunctions of the carburetor "ozone" and methods of their elimination

DIAGNOSTICS OF MALFUNCTIONS OF THE CARBURETOR "OZONE" AND METHODS OF THEIR ELIMINATION

Most irregularities in the operation of the carburetor or other element of the power system, as a rule, immediately affect the operation of the engine. He can start badly, not develop full power, stall or unstable idling.

The search for causes is further complicated by the fact that some faults in the ignition system have similar symptoms and can be mistaken for a problem in the power supply system. The main malfunctions of the ignition system are listed in and (see page 95).

Below are the most common malfunctions of the carburetor and other elements of the power system. turn the throttle lever two or three times. This will activate the accelerating pump.

If there is fuel in the float chamber, it will be injected from the accelerator pump sprayer into the first mixing chamber of the carburetor. If this does not happen, the float chamber is empty. This means that fuel does not enter the float chamber. After making sure that there is fuel in the fuel tank, we check its flow to the pump.

The most likely reasons for impeding fuel delivery to the pump are a clogged strainer, fuel pick-up tube, or fine fuel filter, or a clogged or pinched fuel line. We check the throughput of these elements by blowing them with air. To do this, remove the fuel tank cap.

If there is no fine fuel filter, disconnect the hose from the suction connection of the fuel pump. If the filter is installed, remove the hose from its inlet fitting. Blow out the fuel line and the fuel intake strainer with compressed air towards the fuel tank (see pages 40 and 46). We replace the fine fuel filter.

A defective fuel tank ventilation system can prevent fuel from flowing to the pump.

The main malfunctions of the OZON carburetor and other elements of the power system

O possible malfunctions power systems can be judged by the characteristic signs of the car's behavior on the road.

There are several such signs: Failure - when the accelerator pedal is pressed, the car continues to move at the same speed for some time (several seconds), or with deceleration, and only then starts to accelerate. Dash - similar to failure, but shorter.

Twitching - several jerks following each other. Wobble - several consecutive failures. Sluggish acceleration - the vehicle is not accelerating sufficiently.

Also, possible malfunctions of the engine power supply system can be judged by the following features: - impossibility of starting the engine; - Difficulty starting a cold engine; - Difficulty starting a hot engine; - unstable engine idling;

- increased or decreased idle speed; - increased consumption fuel. The technical condition of the engine also plays an important role. Wear of camshaft cams, displacement of valve timing, violation of thermal clearances, burnout of valves, uneven or low compression in the cylinders lead to a loss of power and increased fuel consumption.

With worn-out parts of the piston group, crankcase gases and oil vapors, getting into the cavity above the carburetor, clog the filter element of the air filter, settle on the jets and other elements of the carburetor, making their work difficult. The engine does not start or immediately stalls after starting.

This may be caused by an insufficient amount or lack of fuel in the float chamber, or by a violation of the composition of the mixture (too rich or, conversely, insufficiently enriched).

To check the presence of fuel in the float chamber, remove the cover of the air filter housing - When unscrewing the cap of such a tank after a long trip, a characteristic hissing sound of intake air may be heard.

If, with the tank plug removed, the engine runs stably in all modes, and after installing the plug after a while, interruptions begin, especially under heavy load, it means that the tube of the tank ventilation system at the Zhiguli is clogged or pinched, or the fuel tank ventilation valve at the Moskvich is faulty "Or Izh.

note

We check the throughput of the Zhiguli fuel tank ventilation system tube by blowing it with air. We replace the faulty fuel filler cap of the Moskvich and Izh fuel tank. If fuel is supplied to the suction connection of the pump, but is absent from its discharge connection, the pump or its drive is faulty. To check the pump, remove the hoses from its fittings.

Turning the engine crankshaft, we find a position in which the diaphragm rod of the fuel pump is not preloaded. When pushing the manual pump lever, the resistance of the stem spring and diaphragm should be felt. First, we check the presence of a vacuum in the suction cavity of the pump.

Finger tightly close the suction connection of the pump and press the lever of its manual drive several times. In a working pump, a vacuum is created in the suction cavity, which can be felt with a finger. If no vacuum is generated, the pump is most likely defective. We remove the pump from the car. We lower its suction fitting into a container with kerosene or diesel fuel and we pump liquid using a manual drive. In a working pump, a pulsating jet will appear from the discharge connection. This indicates that both valves are movable and the working diaphragm of the pump is in good order. After making sure that the pump is pumping the fuel, we check its suction valve for leaks. To do this, typing into the pump

fuel, tightly close the discharge connection with your finger. Using a manual drive, we create fuel pressure in the fitting and wait a few seconds, after which we release our finger. Fuel should spray out of the nozzle, indicating the presence of pressure and, accordingly, the tightness of the suction valve.

If the pump from the manual drive works, but after installation on the engine does not, then its drive is faulty. We check the serviceability of the drive, if necessary, adjust the amount of protrusion of the pusher.

If the fuel pump is in good working order and there is no fuel in the carburetor float chamber, we check the throughput of the fuel supply hose to the carburetor, the carburetor mesh filter and, last of all, the serviceability of the fuel valve needle.

It is unlikely that the fuel valve needle will jam in the closed position and is possible only if there is no pull-off fork connecting the valve needle to the float. We rinse the clogged mesh filter with acetone, after removing it from the carburetor body, blow through the filter with compressed air and reinstall it (see p. 54). Replace the defective fuel valve assembly (see page 57).

A violation of the composition of the mixture can be caused by an incorrect position of the air damper, which is possible when its axle, lever or drive rod is jammed, in case of a malfunction of the starting device or improper adjustment of it.

The depletion of the mixture both when starting the engine and during its operation is caused by a low fuel level in the float chamber, suction of extraneous air into the intake pipe, at the joints of the carburetor with the pipeline, the pipeline with the block head, and also through the hose of the vacuum brake booster.

At negative ambient temperatures, water can freeze in the channels of the carburetor, fuel line and clog them with ice plugs, as well as freeze up the mixing chambers in the diffuser area. As a result, a drop in engine power is observed, or it stops.

Absence or unstable idle speed during proper operation of all other carburetor systems, regardless of modification, are possible due to clogged nozzles and idle channels, loosely wrapped solenoid valve, damage to rubber sealing rings of "quality" and "quantity" screws.

In the presence of the EPHH system, in addition to those listed above, such malfunctions are likely as incomplete screwing of the fuel nozzle holder, malfunction of the control unit, electro-pneumatic valve or other elements of the EPHH, damage to the economizer diaphragm. On modifications without EPCH, the probable reasons may also be incomplete screwing or a malfunction of the solenoid valve.

Since the transition system of the first chamber is combined with the idle system, at unstable idle speed, the engine may fail or stop when the vehicle starts moving smoothly. We wash and blow the clogged channels after partial disassembly of the carburetor. We replace defective parts.

Increased or decreased idle speed can be caused by improper idle speed adjustment, increased or decreased fuel level in the float chamber, clogged fuel or air nozzles, air leaks into the carburetor, into the intake manifold at the joints or through connecting hoses, or incomplete opening of the air damper ...

Unstable engine idling may be the result of too poor regulation of the mixture composition, or the suction of extraneous air into the carburetor or into the intake manifold. Difficulty starting a cold engine is possible if the starting device is incorrectly adjusted.

Incomplete closing of the air damper leads to a lean mixture and, accordingly, to an insufficient concentration of fuel vapors in the cylinders. If it is not slightly opened after starting the engine, the fuel mixture is re-enriched, and the engine “chokes”.

Difficulty starting a warm engine is most often associated with the flow of a rich mixture into the cylinders due to the increased fuel level in the float chamber. The reason is a violation of the adjustment of the float mechanism, or a leaking fuel valve. Increased fuel consumption. Elimination of this malfunction is the most difficult - there are too many probable causes.

First, you need to make sure that there is no increased resistance to the movement of the car, which is facilitated by the braking of the pads on discs or drums, violation of the wheel alignment angles, loading the car, deterioration of aerodynamic characteristics (when installing additional equipment outside the car]. Driving style plays an important role in fuel consumption.

Clogging of the air nozzles, a malfunction of the EPCH system (if the carburetor is equipped with this system), a loosely wrapped solenoid valve or idle fuel jet holder and, as a result, fuel leakage between the nozzle and the channel walls, incomplete opening of the air damper, leading to a permanent re-enrichment of the mixture.

If fuel consumption has increased after repairing the carburetor, the fuel jets may have been mixed up, or others with larger bore diameters have been installed. A deep dip, up to the engine stopping when the throttle valve of one of the chambers is opened, can be caused by a clogged main fuel jet. When the engine is idling, its fuel consumption is low.

When trying to reach full loads, fuel consumption increases sharply, the patency of clogged fuel jets is not enough and a failure occurs in the engine. Light jerking of the car in motion, sluggish acceleration with a smooth pressing of the gas pedal are most often caused by too low fuel level in the float chamber with incorrect adjustment of the float mechanism.

Sluggish acceleration of a car on which a carburetor with a pneumatic throttle valve of the second chamber is installed is most likely associated with an incorrect adjustment or a malfunction of the pneumatic actuator of the throttle valve of the second chamber. The main reasons for the failure of the pneumatic actuator are the suction of extraneous air into the vacuum supply channel to the pneumatic chamber, damage to the diaphragm of the pneumatic actuator, jamming of the throttle valve or its axis, breakage of the intermediate lever spring. Air leaking into the system is possible at the joints of the carburetor body with the throttle valve body, fastening the pneumatic drive body to the carburetor body and the body cover to the pneumatic drive body. The jamming of the damper in the closed position is caused by incorrect adjustment of the screw-stop of the throttle lever of the second chamber. It is possible for the second chamber flap lever to touch the intake manifold flange. Dips, jerks, rocking of the car, which are more common at increased loads and disappear when switching to idle, are associated with interruptions in fuel supply. This can be caused by air leaks into the intake tract, leaking fuel pump valves, clogged mesh filters in the fuel intake, fuel pump or carburetor, increased resistance to the passage of fuel through the filter.

Dips arising from hard pressing the gas pedals and disappearing when the engine is running for 2-5 s in the same mode are caused by a malfunction of the accelerator pump.

Before you start troubleshooting the carburetor, you need to make sure that the fuel supply system is working properly. The main work on its repair is given in the chapter "Maintaining the power supply system".

note

ATTENTION! Be careful when repairing the power system! Spilled gasoline and other flammable liquids can cause a fire. ”Do not turn on or off electrical appliances - a spark that escapes can cause an explosion. To clean the carburetor, use kerosene or special flushing fluids and a brush with moderately stiff bristles.

Individual parts of the carburetor can be washed out with acetone. ♦ Use gloves to avoid exposing your hands to liquids. Work must be carried out in a well-ventilated area or outdoors. ♦ It is not recommended to wipe the carburetor parts and cavities with a lint cloth.

Even the smallest fibers separated from it enter the channels and jets, which can lead to subsequent adhesion of dirt on them, reducing their throughput or clogging.

Laboratory work No. 6

Topic: MOT and TR of the carburetor power supply system

Engine.

2. Purpose: To study the technical process of checking and adjusting the fuel level in the carburetor float chamber.

3. Tasks: Get skills in maintenance and repair of the power supply system carburetor engine.

4. Students should know:

Failures and malfunctions of the power supply system of the carburetor engine, their causes and symptoms. Initial, permissible and limiting values ​​of the parameters of the carburetor, methods and technology for their determination, work on maintenance carburetor and fuel pump.

Should be able to:

perform maintenance work on the power supply system devices, check and adjust the fuel level in the carburetor float chamber.

Methodical instructions for students in preparation for the lesson.

5.1. Literature: "Maintenance and repair of cars" Epifanov. "Cars" Bogatyrev, "Construction and operation Vehicle"Rogovtsev and others.

5.2. Review questions:

Malfunctions, remedies and scope of work for system maintenance

power supply of the carburetor engine;

Diagnosing the carburetor and fuel pump using instruments.

Control and correction of students' knowledge (skills).

6.1. Conduct safety briefing during laboratory work.

6.2. Methodical instructions for performing the work.

6.2.1. Tools, equipment and devices:

Metal ruler;

Set of wrenches;

Screwdriver;

The main malfunctions of the power supply system of the carburetor engine.

Obvious malfunctions of the power system include leakage and leakage of fuel from fuel tanks and pipelines,

"Failures" of the engine at a sharp opening of the throttle valve due to the deterioration of the accelerator pump.

Implicit malfunctions include contamination of the air filters, breakthrough of the diaphragm and leaks of the fuel pump valves, leakage of the needle valve and change in the fuel level in the float chamber, change (increase) in the throughput of the nozzles, incorrect adjustment of the idle system.

The identification of implicit malfunctions of the carburetor and the gasoline pump is carried out by running and bench tests, as well as by assessing the state of individual elements after removing the carburetor and its preventive bulkhead, adjusting and testing in shop conditions.

6.2.3. Checking and adjusting the fuel level in the carburetor float chamber.

Check the fuel level in the carburetor float chamber different ways... In carburetors of K-126 models - visually on the risks of the viewing window while the engine is running at the minimum crankshaft speed, applying a ruler to the viewing window and determining the distance from the fuel level to the plane of the connector of the upper part of the carburetor.

Adjusting the fuel level in the K-151 carburetor of the GAZ-3102 car

"Volga" is carried out by bending the tongue 4 (Figure 6.1) of the lever of the float 1. In this case, the float should be in a horizontal position, and the stroke

Valve 3 should be in the range of 2.0 ... 2.3 mm. The valve travel is adjusted by bending the tongue 2 of the actuator lever. The fuel level should be within 20 ... 23 mm from the plane of the float chamber connector.

On carburetors of VAZ-Zhiguli and Moskvich cars, the fuel level is checked when the top cover carburetor under-

by bending the stop of the float bracket to ensure dimension A (Figure 6.2)

equal to 6.5 to 0.25 mm and dimension B equal to 8 0.25 mm, with the lid in an upright position. To increase the fuel level, the stop is bent down, and to decrease - up.

Rice. 6.2. Setting the fuel level in the "Ozone" type carburetor float chamber: 1 - carburetor cover; 2 - the saddle of the needle valve; 3 - emphasis; 4 - needle valve; 5 - ball of the locking needle; 6 - detachable plug of the valve needle; 7 - float bracket; 8 - tongue; 9 - float.

On VAZ-2108 engines, the distance between the float 1 and the gasket 4 adjacent to the cover 5, which determines the fuel level, is 1 0.2 mm (Figure 6.3), while the cover is horizontal

float up. The fuel level is regulated by bending the tongue down to increase the level and up to decrease it. The thrust surface of the tongue should be perpendicular to the axis of the needle valve 3 and should not have dents or nicks.

The fuel level also depends on the tightness of the float, correct installation, freedom of movement. To check the tightness of the float, it is placed in hot water with a temperature of at least 80 0 C. In case of leakage, bubbles appear from it. After removing the fuel from the float, seal the damaged area and check its weight.

Control questions.

1. The main malfunctions of the power supply system.

2. Checking and adjusting the fuel level in the carburetor float chamber.

3. Checking the tightness of the float and repairing it.

Report.

Laboratory work No. 6.

Diagnostics of the power supply system of the carburetor engine.

Car (make):

Malfunctions in carburetor engines and how to fix them

Many malfunctions that occur during the operation of carburetor engines are caused by the same reasons as in diesel engines, and the methods for their elimination are similar to the methods for eliminating these causes for diesel engines. Therefore, we will consider only those malfunctions in these engines, the causes of which depend on the design of units and mechanisms.

If the engine does not start, and turning the crankshaft is difficult, then either the connecting rod bearings are overtightened, which happens after repairs, or the oil in the crankcase is heavily thickened. In cold seasons, it is necessary first of all to warm up the engine by pouring into the cooling system first with warm (35-40 ° C) and then hot water (60-70 ° C) J check the tightness of the bearings. If the shaft does not turn at all, then the pistons in the cylinders are jammed, which requires appropriate engine repair.

The engine may not start for other reasons as well. Let's consider them in order.

No gasoline flows into the carburetor float chamber. This can be when there is no fuel in the fuel tank or when the valve of this tank is closed and the filter in the fuel tank sump or fuel line is clogged. In such cases, fill the tank with gasoline, open the tank tap, flush the sump filter or blow out the fuel line.

If the float chamber needle valve is stuck or water freezes at the bottom of the fuel tank, the fuel supply can also be cut off. In the first case, you need to open the carburetor and release the needle valve, and in the second, warm the tank by covering it with rags dipped in boiling water. Do not heat the tank with an open flame.

With an incorrectly adjusted carburetor or a cold engine, poor fuel mixture formation occurs, which makes it difficult to start the engine. In these cases, either adjust the carburetor or warm up the engine. To do this, hot water is poured into the cooling system, and heated oil into the crankcase; the exhaust pipe and the carburetor are covered with rags dipped in boiling water.

Poor mixture formation can also occur with poor fuel, for example, with an admixture of kerosene or water.

If the carburetor produces a mixture that is too "lean" or too "rich", this also makes it difficult to start the engine. A "lean" mixture can be the result of air being sucked in through leaks in the connections and in the intake manifold, clogging of the fuel supply system, lowering the fuel level in the needle chamber of the carburetor due to improper bending of the float lever, clogged nozzles and channels in the carburetor. In these cases, you need to check the tightness of the connections and the condition of the gaskets in air system, tighten the connections and replace the worn out gaskets, restore the fuel supply to the carburetor, give correct position the float lever in the float chamber, blow out the jet and the carburetor channel.

Too "rich" combustible mixture is obtained when excessive suction of fuel during start-up and when the float chamber is overfilled with fuel due to improper bending of the float lever, as well as when the shut-off needle is not firmly seated in the seat or the float falls to the bottom of the chamber.

In the event that there was a fuel transfer during start-up, you need to open the throttle and air dampers, turn the crankshaft and blow out the engine cylinders.

In other cases, you need to give the correct position to the float lever; check that the obturator surface of the needle and its seat are clean, and, if necessary, remove dirt from them; repair the float.

The most common causes of starting difficulties when starting engines with carburetors are faults in the ignition system.

Damage to the conductive wire, poor contact of the wire tips and clamps, improper gap between the electrodes in the spark plugs, the presence of a large carbon deposit on the insulator and the spark plug electrodes, violation of the insulation of the central electrode of the spark plug - all this can lead to the absence or weak spark on the spark plug electrodes, as a result of which the working mixture will not ignite. In these cases, you need to isolate the wire from ground or replace it, strip the wire ends and tighten the clamps, adjust the gap between the spark plug electrodes, clean the spark plug from carbon deposits, replace the plug.
Sometimes the spark between the spark plug electrodes jumps out of time due to incorrect ignition timing or displacement of the breaker cam clutch. In these cases, it is necessary to correctly set the ignition or restore the correct position of the clutch.

Incorrect connection of wires to the candles also causes untimely sparks in the spark plug and is eliminated correct installation wires.

Oily or burning of the breaker contacts, violation of the gaps between the contacts, wear of the breaker lever pad lead to the fact that the magneto interrupts sparking. You can eliminate these malfunctions by wiping the contacts with a clean cloth (preferably chamois leather) soaked in gasoline or alcohol, and if necessary, clean them with a velvet file, adjusting the gap between the contacts or replacing the lever with a new one.

With an excessive amount of oil in the crankcase, the candles are thrown with oil, as a result of which the engine does not start.

Difficulties in starting the engine also arise due to weak compression in the cylinders, which is a consequence of: - lack of lubricant on the cylinder walls, which can be washed off by excessively sucked gasoline; - insufficient clearance between valve stems and pushers of the distribution mechanism; - wear of compression rings, piston cylinders, as well as improper installation of ring locks; - large carbon deposits on the valves, their seats, in the distribution mechanism, as well as burning of the valves; - weakening or breakage of the valve spring of the distribution mechanism; - damage to the copper-asbestos cylinder head gaskets.

In all these cases, it is necessary to repair or replace defective parts, grind the valves, adjust the clearances. If there is no lubricant on the walls of the cylinder, you need to pour a little oil into the holes for the spark plugs and turn the crankshaft several times.

A carburetor engine may not provide the required power for the same reasons as a diesel engine, and, in addition, in the following cases: - operation on an excessively lean or excessively rich mixture, which in both cases leads to overheating of the engine; - too late ignition, which is accompanied by shots in exhaust pipe; - too early ignition, which is accompanied by dull knocks when the engine is cold; - incorrect installation of the valve timing after repair.

The causes of knocking in compression rings, pistons, piston pins, valves and connecting rod bearings, as well as the causes of water and oil leaks in carburetor engines are the same as in diesel engines and are eliminated in the same way as in diesel engines.

One of the malfunctions in the engine is clutch slippage when switched on under load, which usually indicates wear of the friction linings of the clutch drive plate and the ingress of grease on the friction surfaces of the clutch discs or a violation of the clutch adjustment. In the first case, the malfunction is eliminated by changing the linings or the driving disc, in the second - by washing and drying the disc, and in the third - by adjusting the clutch.

If the clutch does not engage at all, this may be due to a misalignment and indicates that the clutch needs to be adjusted.

TO Category: - Motors for rail cranes

The main malfunctions of the power supply system of a gasoline engine with a carburetor are:

• stopping the fuel supply to the carburetor;
• the formation of a too lean or rich combustible mixture;
• fuel leakage, difficult starting of a hot or cold engine;
• unstable idling;
• interruptions in engine operation, increased fuel consumption;
• an increase in the toxicity of exhaust gases in all operating modes.

The main reasons for fuel cut-off can be: Damage to the valves or diaphragm of the fuel pump; clogged filters; freezing of water in the fuel lines. In order to determine the reasons for the lack of fuel supply, it is necessary to disconnect the hose supplying fuel from the pump to the carburetor, lower the end of the hose removed from the carburetor into a transparent container so that it does not fall on the engine and does not ignite it, and pump fuel with the manual priming lever of the fuel pump or turning the crankshaft with a starter. If at the same time there is a jet of fuel with a good pressure, then the pump is in good order.

Then you need to remove the fuel filter of the inlet fitting and check if it is clogged. A pump malfunction is indicated by a poor fuel supply, intermittent fuel supply and a lack of fuel supply. These reasons may also indicate that the fuel supply line from the fuel tank to the fuel pump is clogged.

The main reasons for the depletion of the combustible mixture can be: reduction of the fuel level in the float chamber; sticking of the needle valve of the float chamber; low pressure of the fuel pump; contamination of fuel jets.

If the throughput of the main fuel jets changes, this leads to an increase in the toxicity of exhaust gases and a decrease in the economic performance of the engine.

If the engine loses power,"shots" are heard from the carburetor, and the engine overheats, then the reasons for these malfunctions may be: poor supply to the float chamber, clogging of jets and nozzles; clogging or damage to the economizer valve, air leaks through leaks in the carburetor and intake manifold. Loss of engine power when operating on a lean mixture can occur due to slow combustion of the mixture and, as a result, lower gas pressure in the cylinder. When the fuel mixture is depleted, the engine overheats, because the combustion of the mixture occurs slowly and not only in the combustion chamber, but throughout the entire volume of the cylinder. In this case, the heating area of ​​the walls increases and the temperature rises.

For repair and elimination of defects, it is necessary to check the fuel supply. If the fuel supply is normal, it is necessary to check for air leaks in the joints, for which the engine is started, the air damper is closed, the ignition is turned off and the joints of the carburetor and the intake manifold are inspected. If wet spots of fuel appear, this indicates the presence of leaks in these places. Eliminate defects by tightening the nuts and bolts. In the absence of air leaks, check the fuel level in the float chamber and, if necessary, adjust it.

If the nozzles are clogged, they are blown through with compressed air or, in extreme cases, carefully cleaned with soft copper wire.

Fuel leakage should be eliminated immediately due to the possibility of fire and excessive consumption of fuel. It is necessary to check the tightness of the fuel tank drain plug, the fuel-line connections, the integrity of the fuel lines, the tightness of the diaphragms and the fuel pump connections.

The reasons for the difficult start of a cold engine can be: lack of fuel supply to the carburetor; malfunction of the carburetor starting device; malfunctions of the ignition system.

If it feeds well to the carburetor and the ignition system is working properly, possible reason there may be a violation of the adjustment of the position of the air and throttle valves of the primary chamber, as well as the pneumatic corrector of the starting device. It is necessary to adjust the position of the air damper by adjusting it cable drive and check the operation of the pneumatic corrector.

Unstable engine performance or the termination of its operation at a low crankshaft speed at idle speed can be caused by the following reasons: incorrect installation of the ignition; the formation of carbon deposits on the electrodes of the candles or an increase in the gap between them; violation of the adjustment of the gaps between the rocker arms and the camshaft cams; decrease in compression; air leaks through the gaskets between the head and the intake pipe and between the exhaust pipe and the carburetor.

First you need to make sure that the ignition system and the gas distribution mechanism are in good working order, then check that the throttle valves and their drive are not jammed, and the carburetor idle system is adjusted. If the adjustment does not help to achieve stable engine operation, it is necessary to check the cleanliness of the nozzles and channels of the idling system of the carburetor, the serviceability of the forced idle economizer, the tightness of the connections of the vacuum hoses of the EPXX system and the vacuum brake booster.

After every 15,000–20,000 km of run, check and tighten the bolts and nuts securing the air cleaner to the carburetor, the fuel pump to the cylinder block, the carburetor to the intake pipe, the intake and exhaust pipe to the cylinder head, the exhaust pipe to the exhaust pipe, the muffler to the body ... Remove the cover, take out the filter element of the air cleaner, replace it with a new one. When working in dusty conditions, the filter element is changed after a run of 7000–10,000 km, the fine fuel filter is changed. When installing a new filter, the arrow on its housing should be directed in the direction of the fuel flow towards the fuel pump. It is necessary to remove the cover of the fuel pump housing, remove the strainer, rinse it and the cavity of the pump housing with gasoline, blow out the valves with compressed air and reinstall all the parts, unscrew the plug from the carburetor cover, remove the strainer, rinse it with gasoline, blow it with compressed air and put it on place.

In addition to the listed works, after 20,000–25,000 km of run, the carburetor is cleaned and its operation checked, for which the cover is removed and dirt is removed from the float chamber. The dirt is sucked off with a rubber bulb together with the fuel.

Then the jets and channels of the carburetor are blown with compressed air; check and adjust the fuel level in the carburetor float chamber; check the operation of the EPXX system; regulate the carburetor for compliance with the content of carbon monoxide CO and hydrocarbons in the exhaust gases of cars with gasoline engines.

Fuel system maintenance also includes daily inspection of the fuel line connections, carburetor and fuel pump to make sure there are no fuel leaks. Warming up the engine, you need to make sure that the engine is stable at a low crankshaft speed. To do this, the throttle valves are quickly opened, then they are abruptly closed.

Insufficient filling of the carburetor with fuel may be caused by a malfunction of the fuel pump. In this case, the pump is disassembled, all parts are washed in gasoline or kerosene and carefully inspected to identify cracks and breaks in the housings, leaks in the suction and discharge valves, cranking in the seats or axial displacement of the upper housing nozzles, ruptures, delamination and hardening of the pump membrane, elongation the edges of the hole for the membrane pull. Hand lever and lever spring should work well. The pump filter must be clean, the mesh must be intact and the sealing lip flat. The elasticity of the spring is checked under load. Springs and diaphragms not satisfying technical requirements are subject to replacement.

In the body of the fuel pump, there may be such damages as wear of the holes for the axis of the drive lever, stripped threads for the screws securing the cover, warping of the surfaces of the cover and the housing. The worn holes for the axis of the drive lever are expanded to a larger diameter and the sleeve is inserted; stripped threads in holes can be repaired by cutting larger threads.

The warping of the lid contact plane is eliminated by rubbing on the plate with paste or sanding paper.

If the hole in which the support pin is installed and the working surface in contact with the eccentric are worn out at the pump diaphragm drive lever, then the hole is expanded to a larger diameter, and the working surface is fused and machined according to a template. Worn plate valves are repaired by facing their surfaces while grinding on a lapping plate. After repair and assembly, the pump is tested on a special device.

Carburetor repair.

To repair a carburetor, it is usually removed from the car, disassembled, cleaned and blown through with compressed air its parts and valves; change worn and out-of-order parts, assemble the carburetor, adjust the fuel level in the float chamber and adjust the idle system. It is possible to remove and install the carburetor, as well as fasten and tighten the fastening nuts only on a cold carburetor, with a cold engine.

To remove the carburetor, you first need to remove the air pump, then disconnect the cable and the return spring from the throttle valve control sector, the rod and the sheath of the air damper drive rod. Next, unscrew the fastening screw and remove the carburetor heating block; then the electrical wires of the carburetor limit switch are disconnected, and in some cars, the forced idle economizer. After that, the carburetor mounting nuts are unscrewed, removed and the inlet of the intake pipe is closed with plugs. Install the carburetor upside-down.

In order to disassemble the carburetor cover, you need to carefully push the axis of the floats out of the struts with a mandrel and remove them; remove the cover gasket, unscrew the needle valve seat, fuel supply line and remove the fuel filter. Then unscrew the idle speed actuator and remove the actuator fuel jet; unscrew the bolt and remove the liquid chamber; remove the spring housing clamp, the spring itself and its screen. If necessary, disconnect the body of the semi-automatic starting device, its cover, diaphragm, plunger stop, throttle opening adjusting screw, throttle opening lever pull.

Even taking into account the fact that equipped cars are an outdated solution, such cars continue to be popular in the CIS and have firmly established themselves in the lower price segment. At the same time, a relatively simple carburetor engine requires special attention and needs regular maintenance.

This approach allows you to achieve stable work in different modes, as well as to reduce fuel consumption and the level of exhaust toxicity. Next, we will consider the main malfunctions of the power supply system for engines with a carburetor, which usually arise during the operation of the vehicle.

Read in this article

The power supply system of the engine with a carburetor: features and problems

As known, car engine internal combustion, and regardless of the type of engine and type of fuel (carburetor, injector, gasoline or), it runs on a mixture of fuel and air.

Air is “sucked in” by the engine from the atmosphere, and fuel is supplied from the fuel tank through the fuel lines due to the operation of the fuel pump (mechanical or electrical). The so-called fuel-air working mixture is fuel and air, which are mixed in strictly defined proportions. Then the combustion of the working mixture in the cylinders takes place.

On certain engines, the fuel supply and mixture formation can also be implemented in different ways. V injection motors(except for direct injection engines), the fuel is first fed into the intake manifold through the injectors, and then mixed with the air located there. The mixture then enters the combustion chamber.

In a diesel engine, fuel is injected directly into the combustion chamber, where there is already pre-supplied, compressed and heated air. By the way, the diesel engine has the most complex fuel system.

Normally, the fuel level should be 18-19 mm below the plane of the body and float chamber cover connector. The level is checked through a hole in the body of the float chamber, which is closed with a plug. To adjust the level, in some cases it is necessary to change the thickness of the shims that are located under the needle valve in the float chamber.

With regard to adjusting the idle speed on the carburetor, such adjustments are made using a stop screw that limits the closing of the throttle valves (mixture amount screw) and two screws that allow you to change the composition of the working mixture of fuel and air (quality screws).

What is the bottom line

As you can see, the carburetor, even with its simplicity, still needs periodic maintenance. It is important to understand that the quality of the fuel also plays an important role.

The use of low-grade gasoline with a large amount of foreign impurities leads to the fact that the jets become dirty, as a result of which there are problems with the supply of fuel to the carburetor. It is also important to maintain the overall cleanliness of the power system, to prevent severe contamination of the fuel tank, to monitor the condition of the fuel filter, etc.

Finally, we note that in the CIS, many motorists actively use Weber (Weber), Ozone or Solex (Solex, DAAZ) carburetors. By the way, the latter device has established itself as a reliable and time-tested solution, at the same time amenable to flexible customization.

Read also

Completion and modernization of the carburetor. The main disadvantages of the carburetor injection system and how to eliminate them, tuning. Intake manifold tuning.