Fuel Pump Delivery Quantity, Checking

Diagnostic Procedures

Fuel Pump Delivery Quantity, Checking

Special tools, testers and auxiliary items required

• Hand held remote control (jumper).

• Electrical connector test lead set.

• Fuel pressure test set (high pressure).

• Measuring container, fuel-resistant.

Test conditions

• Battery voltage 12.5 V.

• Fuel filter OK.

• Fuse (ST2) OK.

• Fuel Pump (FP) Control Module (J538) OK.

• Fuel tank at least 1/4 filled.

• Ignition switched off.

Test sequence

- Remove the rear seat bench.

- Remove the screws- arrows - and the right locking flange.





- Disconnect fuel delivery unit electrical harness connector - arrow -.





- Connect a Hand held remote control (jumper) to terminal - 1 - of the fuel delivery unit and to vehicle battery (+).

- Connect a jumper cable from a Electrical connector test lead set to terminal - 4 - of the fuel delivery unit and to vehicle Ground (GND).





- Remove the fuel filler cap from the fuel filler tube.

- Remove the rear engine cover - arrows -.





CAUTION!
Fuel system is under pressure! Before opening system, place clean rags around the connection. Then release pressure by carefully loosening the connection.

- Disconnect the fuel line at the fuel rail - arrow -.





- Connect a Fuel pressure test set (high pressure) to the fuel line.





- Connect a hose - arrow - to pressure gauge and hold it in the measuring container.

- Open the shutoff valve of the pressure gauge. The lever points in the direction of flow.

- Press the switch of the remote control and slowly close the shutoff valve of the pressure gauge.

The fuel pressure should rise.

• Specification: 4 BAR positive pressure.

- Do not move the shutoff valve position.

- Empty the measuring container.

- Press the remote control switch in for 15 seconds.

- Compare the quantity of fuel delivered with the minimum delivery rate in the diagram (cm3/15s).





• Voltage at fuel pump with engine stopped and pump running is approx. 2 volts less than battery voltage.

If the minimum fuel delivery quantity is not obtained, the following malfunctions may be present:

• Fuel lines pinched. Check fuel lines for damage. Repair or replace as necessary.

• Fuel filter clogged. Replace the fuel filter.

• Fuel pump faulty. Check the fuel pump.

Assembly is performed in the reverse order of removal.

- Install fuel line and tighten the line to 28 Nm.

Torque specifications