Repair of K-151 carburetor of GAZ-2705 car
The carburetor should be removed from the engine mainly for flushing from dirt and resins, since most of its systems and elements can be repaired and adjusted without dismantling
It is not recommended to unscrew the screws securing the throttle valves on the axles and remove the dampers unless absolutely necessary, as their displacement can lead to jamming of the dampers in the channels.
The brass connecting tubes of the channels pressed into the body should not be removed in order to avoid violating their tight fit.
The carburetor should be disassembled only as a last resort, if flushing and blowing with compressed air without disassembly does not eliminate the sticking of the throttle and air dampers and does not lead to complete cleaning of the jets and channels from deposits.
Disconnect the air damper rod 1 from the profile lever by removing the cotter pin 2 from the hole on its bent end.
Remove the seven screws securing the cover to the body and remove the carburetor cover
Unscrew the two screws securing the throttle body and, disengaging the connecting earring, remove the body
Unscrew the three fixing screws 1 and remove the cover 2 of the vacuum diaphragm of the carburetor starter.
On the reverse side of the carburetor cover, disengage the bent end of the carburetor trigger diaphragm rod from engagement with the trigger lever.
Remove diaphragm 1 from carburettor cover
Disconnect choke spring 1 from cover pin.
Unscrew the two screws 2 and shine the cover 3 of the ventilation channel of the float chamber.
Remove the screw 4 fastening and shine the atomizer 5 econostat.
Unscrew the fastening screws and remove the starter drive levers.
Carefully remove the heat-insulating gasket from the lower flange of the mounting housing, and remove
Remove two screws 1 microswitch 2 of the EPHX system.
Remove cotter pin 4 and remove damper control lever 3 together with profile lever 5 from the shaft.
Unscrew plug 1 of the float axis hole with a screwdriver and remove the aluminum sealing washer located under it.
Using tweezers or round-nose pliers, remove the float shaft and remove float 4 and needle 3 of the shut-off valve.
Unscrew seat 2 from the carburetor body.
Remove the four fixing screws 1 and REMOVE the cover 2 of the accelerator pump together with the lever.
Remove the accelerator pump diaphragm and the release spring located underneath.
Unscrew the hollow fuel supply bolt 1 and remove it together with the manifold 2 and the aluminum sealing washers 3.
Remove the fuel supply screw 1 from the manifold 2 together with the strainer and remove the aluminum sealing washers 3 from it.
Unscrew the drain plug with the sealing washer from the wall of the float chamber.
Using a carefully selected screwdriver (to avoid damage to parts made of brass), unscrew the air 3 and fuel 2 jets of the main metering system, air jets 4 and 5 of the idle and transition system from the body.
Unscrew the screw plugs 1 located on the sides of the housing and unscrew the fuel jets of the idle system and the transition system located under the plugs.
Unscrew the hollow fuel supply screw 6 fastening the accelerator pump nozzle and remove the nozzle 7 together with the sealing aluminum washers.
Unscrew the three fastening screws and remove block 1 EPHX together with the sealing gasket of the carburetor body.
If it is necessary to replace the EPHX diaphragm, unscrew the four screws securing the EPHX valve and remove the valve assembly.
Then, carefully separating the valve cover from the diaphragm, remove the diaphragm together with the spring from the valve body.
to disassemble the throttle actuator mechanism, you need to unscrew the nuts securing the actuator parts on the damper axles, having previously marked the location of the parts on the axles, and remove the parts
After dismantling, wash the carburetor parts in gasoline or thinner, then blow out all the channels in the carburetor parts with compressed air.
Build and install
The assembly of the carburetor assemblies and the carburetor itself as a whole, as well as its installation on the engine, is carried out in the reverse order of disassembly, taking into account the following:
It is necessary to check the mating surfaces of the throttle body for nicks and cracks.
Check the ease of turning the shutters in the housing and the clarity of their return to their original position after removing the force.
Check the mating surfaces of the carburetor body for nicks and warping in the area of the holes for the mounting screws.
All cardboard, paronite and rubber gaskets must be replaced with new ones.
The screws connecting the carburetor body parts should be tightened tightly, but without excessive force, which could lead to deformation of parts made of soft alloys.
The nuts securing the carburetor to the engine intake pipe should be tightened without excessive force and only on a cold engine.
After assembly and installation, the carburetor must be adjusted
K-151 carburetor adjustment
The fuel level in the float chamber is adjusted with the carburetor cover removed.
However, without disconnecting the trigger rod, you can unscrew the screws that secure the cover, lift it up and, having removed the gasket, turn the cover to the side as far as the gaps in the places where the rod is attached will allow.
Pump gasoline into the float chamber with the fuel pump manual priming lever until the level stabilizes.
The distance from the fuel level to the upper plane of the carburetor body should be 21.5 mm.
When the fuel level is below the specified one, it is necessary to bend up the tongue 1 of the float, which abuts against the shank of the shut-off valve needle.
When the tongue is raised, bend it down.
After each bending of the tongue, it is necessary to unscrew the drain plug of the float chamber, drain the gasoline from it and, after screwing the plug back in place, re-pump the gasoline with the fuel pump manual priming lever
You can adjust the starting system directly on the car by fully warming up the engine and connecting a tachometer to it.
Starting the engine with the air filter removed and lightly depressing the accelerator pedal, fully close the air damper with its actuator handle.
Then, use a screwdriver blade to slightly open the air damper as far as the lever mechanism allows. The engine speed should be 2500-2700 min.
If it differs from the specified one, you need to loosen the locknut on the adjusting screw resting against the profile lever, screw or unscrew this screw.
Tighten the locknut tightly after adjustment is complete.
Adjust the idling system on a warm engine with a nonmu tachometer. To do this, with the engine running, set quality screw 2 to a position that ensures maximum idling speed.
Then, using the number 1 screw, set the frequency increased by 100-120 min. After that, tighten the quality screw until the speed is reduced by 100-120 minutes.
This method of adjustment allows you to meet the emission standards. However, a more precise adjustment is recommended using a gas analyzer.
Check the operation of the accelerator pump with the carburetor cap removed after adjusting the fuel level.
When the throttle valves are suddenly opened, an even strong jet of gasoline should come out of the accelerator pump nozzle, reaching the channels of the throttle body without touching the walls of the diffusers.
An uneven and curved jet indicates a partial clogging of the atomizer channels. In the absence of a jet, you should make sure that the fuel supply screw of the atomizer and the delivery valve located in it are clean and in good condition.
If they are in good condition, you should check the cleanliness and serviceability of the diaphragm mechanism of the accelerator pump by disassembling it, as described above.
Checking the control unit and EPHX valve
In addition to the above elements, the power system contains an EPHX control unit 1 and a solenoid valve 2 installed in the engine compartment.
Together with the ineumovalve and the microswitch installed on the carburetor, these devices form the EPHH system, which cuts off the fuel supply in forced idle mode and prevents the engine from spontaneous ignition after the ignition is turned off.
Both devices are non-separable and must be replaced in case of failure.
The solenoid valve is tested directly on the vehicle.
To do this, with the engine idling, remove any of the wires from the valve plug.
The engine should stop immediately. Continued operation of the engine with good carburetor systems and the EPHX pneumatic valve indicates a malfunction of the solenoid valve.
To check the health of the EPHX control unit, connect a voltmeter to the wire connecting the solenoid valve to the control unit and to the ground.
At idle and at an increased speed, the voltage on the solenoid valve plug must be at least 12 V. Then, increasing the crankshaft speed to 2000-3000 min -1, abruptly close the throttle .
At the moment the throttle valve is closed and until the speed drops to 1100 min, there should be no voltage on the solenoid valve plug.
If the voltage remains unchanged when the throttle is released, any wire should be disconnected from the carburetor EPHX microswitch.
If, at a crankshaft speed of more than 1600-1800 min1, a voltage drop of up to 0.5 V or less is detected, there is a short circuit in the microswitch or its installation is disturbed.
If the voltage does not drop, the control unit is faulty. Indirectly, this malfunction is confirmed by the operation of the engine from self-ignition after the ignition is turned off.
Replacing the air filter element
Remove hose 3 for crankcase breather. Disconnect the four spring clips 1 and remove the filter cover 2
Remove the filter element.
Wipe the inside of the filter housing and cover. At the same time, make sure that dust and dirt do not get into the carburetor
Install the new filter element into the filter housing, close the cover and fasten the spring clips. Install the crankcase ventilation hose.
Replacing and adjusting the carburetor air damper rod
Remove screw 4 and pull rod 1 out of the choke control lever. Loosen screw 2 and pull out cover 3 of the rod from the bracket on the carburetor.
Without removing the shell, pull the rod out of it by the handle into the car interior. To replace the thrust sheath, it is necessary to answer unscrew the nut on the bracket under the steering column and pull the rod shell into the passenger compartment.
Insert a new rod into the shell from the interior side and fix it with a screw on the choke control lever.
If the shell was removed, you must first install the shell of the thrust from the passenger compartment and fasten it with a nut on the bracket, then insert the thrust into it.
Adjust the air damper rod. to do this, press the traction handle located under the steering column as far as it will go.
Loosen the screw 4 and fully open the air damper by turning the damper drive lever 5.
Then tighten screw 4. Pull the traction handle towards you as far as it will go, the air damper must close completely.
If this does not happen, loosen the screw 1 and by moving the shell 2 of the rod in the bracket 3 achieve complete closing of the air damper.
Recheck the opening and closing of the air damper by moving the traction control from stop to stop.
K-151 carburetor calibration data
Parameter - Primary Camera - Secondary Camera
Diffuser diameter, mm - 23 - 26
Mixing chamber diameter, mm - 32 - 36
Productivity of the main fuel jet, cm3/min - 225 - 380
Productivity of the main air jet, cm3/min - 330 - 330
Productivity of the idle fuel jet and transition system, cm3/min - 95 - 150
The performance of the first idle air jet and the air jet of the transition system, cm3/min - 85 - 270
Emulsion idle jet capacity 280 -
Performance of the second idle air jet 330 -
Submission of the accelerator pump for 10 full strokes, cm3/min - 10±2.5
Fuel level from the upper plane of the hull, mm - 21.5±1.5
Gap at the lower edge of the air damper after start-up, mm - 6±1