Contents: Fuel pump - check ⤓ Checking the vent ⤓ Checking the pump operation ⤓ Checking the intake valve ⤓
Fuel pump - check
Models with carburetor engine
Warning! Be careful when working with gasoline!
1. Check fuel lines for leaks.
2. If no leak is found, check the fuel pump, after disconnecting the negative battery cable.
Checking the vent
3.3 Check the fuel pump vent (arrow) - if oil or petrol is leaking out, replace the fuel pump
3. Check if fuel or oil is leaking from the vent (3.3). If there is a leak, replace the fuel pump.
Checking the pump operation
4. Disconnect the fuel supply line from the carburetor and place the end of the line in a suitable container.
Connect the negative battery terminal wire. Disconnect the wires from the ignition coil primary winding terminals.
5. Turn the engine crankshaft with the starter for about 10 seconds. If the fuel is ejected in rhythmic portions, then the pump is working properly. If not, replace it.
Checking the intake valve
6. Disconnect the fuel supply hose from the pump. Connect a vacuum gauge to the pump pipe. Crank the engine with the starter.
7. The pressure gauge should register the presence of a constant vacuum. If the pressure jumps, it means that the inlet valve does not provide sufficient sealing and the fuel pump must be replaced.
Models with multi-point fuel injection
8. Release pressure from the fuel system.
3.9 On models with multi-point fuel injection, use a special adapter (MD 998742 or similar) to install the pressure sensor
9. Disconnect the fuel supply pipe from the fuel manifold and connect the pressure sensor (3.9).
10. Start the engine and compare the pressure shown by the gauge with the pressure specified in the specifications section.
11. Disconnect the vacuum hose from the pressure regulator and cap the end of the hose. Read the pressure gauge readings.
12. Crank the engine two or three times. Start the engine and read the pressure sensor.
13. Gently pinch the return line hose of the pressure regulator and check for pressure.
14. If the fuel pressure was low in both tests, the fuel filter or fuel supply line is clogged or the fuel pump is faulty.
15. If the pressure was high when the pressure regulator was connected, it means that the regulator is faulty or is not receiving vacuum.
16. If the pressure was low when the regulator was connected, and normal after disconnecting the regulator, then the pressure regulator is faulty.
Models with two-point fuel injection
17. Release pressure from the fuel system.
3.18 On models with two-point fuel injection, use a special adapter (MD 998742 or similar) to install the pressure sensor
18. Disconnect the fuel supply pipe from the throttle body and connect the pressure sensor (3.18).
19. Start the engine and compare the pressure shown by the gauge with the pressure specified in the specifications section.
20. If the pressure is low, check to see if the fuel filter is clogged, the pressure regulator is faulty, there is a leak in the fuel supply line, and the fuel pump is working properly.
21. For more detailed diagnostics, please contact a specialist.