Attention: Observe fire safety regulations, do not work with open fire! To check the pump feed, the tank must be at least half full.
Remove the fuel pump relay.
Connect the voltmeter to the fuel pump. Close contacts 7 and 8 on the relay board.
The pump should start working, and the voltage on it should be at least 11.5 V. Otherwise, check the battery, and accordingly, the wiring according to the diagram.
Remove the test wire.
Connect the ammeter to contacts 7 and 8. The current at the fuel pump should be approximately 6 A. If the current exceeds 7 A, replace the pump.
Unscrew the fuel return line (51) from the diaphragm pressure regulator (40). Screw a section of hose approximately 50 cm long to the regulator. Tip: sealing cone with union nut with M14.5x1.5 thread. The tip is connected to the hose with a clamp. Hold the hose over a container.
Material created based on the website MercedesMAN
Short-circuit contacts 7 and 8 of the fuel pump relay block for a maximum of 50 seconds.
The pump output should be approximately 1 liter. Otherwise, perform the following tests:
- Unscrew the union nut from the fuel supply nipple to the dispenser, remove the mesh and blow it out, replace it if necessary.
- Inspect the hoses for kinks and dents; replace if necessary.
- Clamp the short hose on the fuel storage tank with a screw clamp and check the pump feed again. If the specified value is reached, replace the fuel storage tank.
- Replace the fuel filter and check the fuel supply again. If the supply is still low, replace the pump.
- Screw the pipeline with a force of approximately 10 Nm to the pressure regulator.
- Insert the fuel pump relay.