Contents: Carburetor engines ↡ Fuel Injected Engines ↡
1. Round gasket. 2. Filter. 3. Cover. 4. Sealing ring.
Carburetor engines
The fuel pump is driven by a pushrod via a cam on the oil pump drive shaft. The individual parts of the fuel pump are shown in the figure. Removal and installation are straightforward.
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 short-circuiting the ground wire to terminal 1 of the ignition coil.
- Remove the inlet and outlet hoses from the fuel pump.
- Attach a pressure (vacuum) gauge to the pump inlet.
- Crank the engine with the starter until the vacuum reading no longer increases.
- Compare the obtained value with the specified 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:
- Connect the pressure gauge to the pump outlet.
- Turn the engine over with the starter until the pressure value no longer increases.
- Compare the obtained value with the specified one. It should not decrease by more than 0.05 bar during the first minute.
If the vacuum or pressure is not achieved, check whether excess air is being sucked in through the rubber gasket (1). After inspection, replace the gasket and repeat the check.
Fuel Injected Engines
Vehicles with fuel injection are equipped with an electric fuel pump.
1. Pressure limiting valve. S. Inlet pipe. D. Outlet pipe. R. Drain pipe
This pump is non-serviceable and non-repairable. If faults occur that point to the fuel pump, then the pump performance should be measured as follows:
Disconnect the fuel return hose from the fuel portion divider (fuel dispenser).
Self-made fuel hose (see picture) attach to the fuel portion divider (dispenser) and lower into the measuring vessel.
Remove the fuel pump relay (arrow).
Short-circuit contacts 1 and 2 to supply current to the fuel pump.
After 30 seconds, remove the jumper.
If the pump performance (amount of fuel in a measuring vessel in 30 sec) less than 1 l/30 sec, then the following elements must be checked:
- Check the voltage at the fuel pump. Its value should reach at least 11.5 V.
- Check fuel lines for throttling and clamping.
- Check the mesh 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 the fuel filter. If the performance is still low, the fuel pump should be replaced.
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After checking, reconnect the fuel return hose and plug the relay back in. Removing and installing the fuel pump is easy.