Generic Scan Tool - Fuel Supply

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 min. 12.5 V.
- Fuel filter OK.
- Fuse S228 (position 28) OK.
- Fuel Pump (FP) Control Module J538 OK.
- Fuel tank at least 1 / 4 filled.
- Ignition switched off.

Test procedure
- Perform a preliminary check to verify the customers complaint. General Diagnosis.

Start diagnosis
- Remove the rear seat bench.







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







- Remove the wiring harness and the electrical harness connector - arrow - from locking flange opening and position aside.







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







- Push the battery cover to the right - arrow 1 - and remove it upward - arrow 2 -.







- Release the retaining clip - arrow A - and open the positive terminal cover - 2 -.
- 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 (cu.cm/15 s).

NOTE: 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 reverse order.







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

Torque specifications

Component Nm
Fuel line to fuel rail 28