The power system consists of a fuel tank, fuel lines, a fuel pump, a sediment filter, a fine fuel filter, a carburetor with a throttle and air damper drive, and an air filter.

Fuel from the tank flows through the fuel line to the diaphragm pump. It is driven by a camshaft eccentric, which acts on the pump drive lever.

A filter made of fine brass mesh is installed on the inlet fitting of the pump.

When the engine is not running, fuel is pumped into the carburetor using the manual pump drive lever.

There is a hole in the bottom of the pump housing. Leakage of fuel from it indicates leakage of the diaphragm.

Further, the fuel passes through the fuel filter, which consists of a housing, a plastic sump cup and a filter element.

Then the fuel enters the K-151 carburetor.

Scheme of the fuel system with the ZMZ-402 engine

The air filter is a dry type, with a replaceable filter element made of porous cardboard, mounted on the carburetor through a rubber gasket.

To reduce air intake noise, the filter is equipped with an air intake corrugated hose connected to a metal pipe located on the right side of the splash guard.

When the ambient temperature is below 5 ° C, to supply heated air to the carburetor, the air intake hose must be disconnected from the nozzle located on the mudguard shield and connected to the nozzle of the screen mounted on the engine exhaust pipe.

It is necessary to use filter elements with the following designations:

3102-1109013-02 (-03-04-05,-Ob) or 31029-1109013 (-01-02,-03)

Throttle and choke actuator

The B-9V fuel pump is a diaphragm type, driven by an eccentric located on the engine camshaft.

The fuel pump consists of prefabricated housing units with a diaphragm 8 and a drive lever 9, a head with valves 4 and 7 and a cover. a diaphragm of four petals made of varnished fabric is clamped between the body and the pump head.

fuel pump

The diaphragm rod is sealed with a rubber seal 2. The valve consists of a cage made of zinc alloy, a rubber valve and a brass washer, pressed by a spring (made of bronze wire).

A filter 6 made of fine brass mesh is installed above the suction valves of the pump. to fill the carburetor with fuel when the engine is not running, the pump has a device for manual drive.

To control the tightness of the diaphragm in the pump housing there is a hole with a strainer 3.

fuel filter sump

The K-151 carburetor consists of three main detachable parts connected through sealing gaskets with screws.

Upper part - carburetor cover includes an air pipe, divided into two channels, with an air damper in the channel of the first chamber.

The middle part consists of a float and two mixing chambers and is the carburetor body.

The lower part - the throttle body includes mixing pipes with throttle valves of the first and second chambers of the carburetor.

The gasket between the middle and lower parts of the carburetor is sealing and heat-insulating.

Structurally, the carburetor consists of two mixing chambers - the first and second. Each of the carburetor chambers has its own main dosing system.

Idle system - with quantitative adjustment of constant mixture composition (autonomous idling system).

In the second chamber of the carburetor there is a transitional system powered by fuel directly from the float chamber, which comes into operation at the moment the throttle valve of the second chamber is opened.

The accelerator pump is a diaphragm type. to enrich the combustible mixture at full load, an econostat is provided in the second chamber.

Launcher Schematic

When the accelerator pedal is released, the contacts of the microswitch 35 must be open.

The fuel cut-off system works as follows.

When the accelerator pedal is released and the engine speed is more than 1400, the control unit does not apply voltage to the solenoid valve, as a result of which atmospheric air enters the forced idle economizer through the channels of the solenoid valve, the valve of which closes the idle channel.

In the event of a malfunction of the fuel cut-off system (the engine does not start or “stalls” when the throttle pedal is released), you must first make sure that the electrical contacts of the system elements are reliable, after which you should sequentially check the operability of the solenoid valve, microswitch and control unit .

To check the solenoid valve and the microswitch, it is necessary to disconnect the electrical connector of the control unit, turn on the ignition (do not start the engine!) And the engine compartment, smoothly open and close the carburetor throttle several times with one hand, and hold the solenoid valve with the other.

With a working solenoid valve and a fuse, and with a working and correctly adjusted microswitch, the operation of the solenoid valve (vibration, clicks) should be felt.

To check the control unit, you must insert the connector into the unit, turn on the ignition, start the engine and warm it up.

Then, from the side of the engine compartment, open the throttle valves about 1/3 of the way with one hand, hold the solenoid valve with the other.

Release throttle quickly. At the same time, if the control unit is corrected, the solenoid valve should turn off, and when the crankshaft speed drops to about 1050, the solenoid valve should turn on.

All carburetor systems are connected to a float chamber, the fuel level in which is maintained by float 2 and fuel valve 1