1. Round gasket. 2. Filter. 3. Cover. 4. O-ring.
Carburetor engines
The fuel pump is driven by a pushrod through a cam on the oil pump drive shaft. Individual parts of the fuel pump are shown in the figure. Removal and installation do not present any problems.
The pump cannot be repaired. It can be checked in the installed state. The necessary operations are carried out as follows:
- Short-circuit the ignition system by connecting the ground wire to terminal 1 of the ignition coil.
- Remove the inlet and outlet hoses from the fuel pump.
- Attach a pressure gauge (vacuum) to the pump inlet.
- Crank the engine with the starter until the vacuum value displayed no longer increases.
- Compare the received value with the given one. It should decrease by a maximum of 95 mbar within the first minute.
- Check the pressure of the fuel coming from the fuel pump:
- Attach a pressure gauge to the pump outlet.
- Turn the engine over with the starter until the pressure value no longer rises.
- Compare the received value with the given one. It must not decrease by more than 0.05 bar within the first minute.
If the vacuum or pressure is not reached, then check whether excess air is sucked in through the rubber gasket (1). After the inspection, replace the gasket and repeat the test.
Fuel injected engines
Vehicles with fuel injection are equipped with an electric fuel priming pump.
1. Pressure relief valve. S. Inlet. D. Outlet. R. Drain pipe
This pump is maintenance-free and non-repairable. If there are malfunctions indicating the fuel pump, then the pump performance should be measured as follows:
Disconnect the fuel return hose from the fuel divider (fuel dispenser).
Self made fuel hose (see picture) attach to batch divider (dispenser) fuel and lower into a measuring vessel.
Pull the fuel pump relay (arrow).
Jumper pins 1 and 2 to supply current to the fuel pump.
Remove the jumper after 30 seconds.
If the pump performance (the amount of fuel in the measuring vessel in 30 seconds) less than 1 l/30 sec, the following items should be checked:
- Check voltage at fuel pump. Its value should reach a minimum of 11.5 V.
- Check fuel lines for throttling and clamping.
- Check the grid on the inlet of the fuel portion divider for patency.
- Disconnect the fuel return line between the fuel accumulator and the inlet damper and check the performance again. If the above value is reached, replace the fuel accumulator. Replace fuel filter. If the performance is low in this case, then the fuel pump should be replaced.
After checking, reconnect the fuel return hose and plug the relay back in. Removal and installation of the fuel pump is not difficult.