Fuel Pressure and Residual Pressure before High Pressure Pump, Checking

Fuel Pressure and Residual Pressure before High Pressure Pump, Checking

Special tools, testers and auxiliary items required

• Fuel Inj. Pressure Gauge-CIS (V.A.G 1318)

• Adapter (V.A.G 1318/10-12) and adapter (V.A.G 1318/15)

• Remote Control (V.A.G 1348/3A) with Remote Control (V.A.G 1348/3-3)

• Measuring container, fuel-resistant

Test Conditions

• Battery voltage at least 12.5 V.

• Fuel filter OK.

• Fuel tank minimum 1/4 full.

• Fuel pump (FP) control module (J538) OK; checking.

• Ignition switched off.

Fuel Pressure, Checking

- Fold forward the right backrest of rear seat, if necessary.

- Remove luggage compartment floor trim.

- Remove cover for locking flange - arrows -.






- Carefully release and disconnect electrical harness connector - arrow - at locking flange.






- 2. Tape (V.A.G 1348/3-3) with insulating tape - arrow - to prevent a short circuit.






- Route (V.A.G 1348/3A) toward the front in engine compartment.

- Connect alligator clip to ground (GND) point in engine compartment.

- Connect the contact - 1 - to the battery positive with a self-made adapter cable.

• For safety reasons, install a fuse - A - in the cable.

- Remove the rear engine cover - top arrows -.







There is a risk of contamination.

• Note rules of cleanliness for working on the fuel injection system. Refer to => [ Clean Working Conditions ] Multiport Fuel Injection.


There is a risk of injury because the fuel is under very high pressure.

• Before opening high pressure area of the fuel injection system, fuel pressure must be relieved to residual pressure.

- Reduce fuel pressure in high pressure area. Refer to => [ Before Opening High Pressure Fuel Injection System ] Service and Repair.

- Remove the fuel supply hose from the high pressure pump - arrow - and free it up.






- Connect the (V.A.G 1318) with the adapters (V.A.G 1318/11) and (V.A.G 1318/15) in the fuel line.






- Connect assisting hose - arrow - on pressure gauge and hold it in a measuring container.

- Open the shut-off valve on the pressure gauge.

• The lever points in the direction of flow.

- Bleed fuel system by briefly pressing remote control.

- Close the shut-off valve on the pressure gauge.






• Lever stands perpendicular to direction of flow - arrow -.

- Press the remote control switch long enough until the pressure gauge stops registering an increase in pressure.

• Specified value: approximately 6 bar pressure.

- If the specified value is not reached, check the fuel pump delivery rate.

Residual Pressure, Checking

- Check for leaks and constant pressure, watch the manometer to see if there is a drop in pressure.

• After 10 minutes there must be a residual pressure of at least 3 bar.

If the holding pressure drops below 3 bar:

• Check connection between pressure gauge and fuel line for leaks.

• Check the pressure gauge for leaks.

• Check fuel lines and their connections for leaks.

• Replace the fuel filter with an integrated fuel pressure regulator.

• Replace fuel pump.

Assembling

• Tightening specifications, refer to => [ High Pressure Pump Overview ] High Pressure Pump Overview.

Assembly is performed in reverse order of removal, noting the following:


There is a risk of injury because the fuel is under very high pressure.

• Before disconnecting pressure gauge, release pressure by opening shut-off valve. Hold a container in front of connection for this.