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
- Pressure gauge V.A.G 1318
- Adapter V.A.G 1318/11
- Adapter V.A.G 1318/12
- Remote control V.A.G 1348/3 A with adapter cable V.A.G 1348/3-3
- Connector test set V.A.G 1594 C
- Measuring container, fuel-tight

Test conditions
- Battery voltage min. 12.5 V.
- Fuel filter OK.
- Fuel tank at least 1/4 filled.
- Fuel Pump (FP) Control Module J538 OK; checking.
- Ignition switched off.

Checking fuel pressure
- Remove rear seat bench.







- Unbolt cover for right locking flange - arrows -.







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







- Connect remote control V.A.G 1348/3 A with connection V.A.G 1348/3-3 to contact - 1 - using an adapter cable from connector test set V.A.G 1594 C.
- Using insulating tape, tape over second contact of connection V.A.G 1348/3-3 to prevent a short circuit - arrow -.
- Connect contact - 4 - to vehicle Ground (GND) using a jumper cable from connector test set V.A.G 1594 C.
- Route switch of remote control V.A.G 1348/3 A forward into engine compartment.







- Push cover over positive terminal pick-off to right - arrow 1 - and remove it upward - arrow 2 -.







- Release retaining clip - arrow - and open cover - 2 - over positive terminal pick-off.
- Connect alligator clip to vehicle battery (+) - 3 - .

NOTE: Ignore - 1 -.







- Pull rear engine cover off - arrows -.







- Remove bolts - 1 -.
- Disengage retaining clip - 2 - and remove rear engine cover bracket.

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







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







- Connect pressure gauge V.A.G 1318 to fuel line using adapter V.A.G 1318/11 and V.A.G 1318/12.
- Connect an assisting hose - arrow - to pressure gauge and hold it in a measuring container.
- Open shut-off valve of pressure gauge. The lever points in direction of flow.
- Bleed fuel system, by briefly pressing the remote control.







- Close shut-off valve of pressure gauge. Lever stands perpendicular to direction of flow - arrow -.
- Hold switch of remote control until no more pressure increase is observed on fuel pressure gauge.
- Specification: approx. 6 bar positive pressure

If specification is not obtained:
- Check delivery quantity of Fuel Pump (FP).

Checking residual pressure
- Check for leaks and for residual pressure by observing the pressure loss on pressure gauge.
- After 10 minutes there must be a residual pressure of at least 3.75 bar.

The holding pressure drops below 3.75 bar:
- Check connection between fuel pressure gauge and fuel line for leaks.
- Check pressure gauge for leaks.
- Check fuel lines and their connections for leaks.
- Replace fuel filter with integrated fuel pressure regulator.
- Replace fuel pump.

Assembly is in reverse order of removal. Note the following:

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

Torque specifications
Fuel supply line to fuel rail 25 Nm