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 VAG1318
- Adapter V.A.G 1318/11
- Adapter V.A.G 1318/12







- Remote Control V.A.G 1348/3A with adapter cable V.A.G 1348/3-3
- Measuring container, fuel-resistant







Test conditions:
- Battery voltage at least 12.5 Volts.
- Fuse on fuse panel S228 (position 28) OK.







- Fuel Pump (FP) Control Module J538 OK; checking
- Fuel filter OK.
- Fuel tank minimum 1/4 full.

Test sequence
- Switch off ignition.

Sedan:
- Remove carpeting in luggage compartment.
- Fold forward the right backrest of rear seat, if necessary.

Wagon:
- Remove left 1/3 backrest.
- Remove left side trim in luggage compartment and dirt tray.

All:







- Remove locking flange cover - arrows - .







- 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 the connector test set V.A.G 1594 C .
- Using insulating tape, tape over the second contact of adapter cable 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 .
- Connect alligator clip to vehicle battery (positive).
- Remove fuel filler cap from fuel filler tube.







- Remove 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 fuel supply line - arrow - .







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







- Close shut-off valve on Pressure Gauge V.A.G 1318 . The shut off valve lever points in the direction of flow. - arrow - .
- Hold switch of the remote control until no more pressure increase is observed on the Pressure Gauge V.A.G 1318 .
- Specified value: approx. 6 bar (5 to 7 bar) positive pressure.

If specification is not obtained:
- Check delivery rate of fuel pump.

Checking residual pressure
- Check for leaks and residual pressure by observing pressure drop on Pressure Gauge V.A.G 1318.
- 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 V.A.G 1318 and fuel line for leaks.
- Check Pressure Gauge V.A.G 1318 for leaks.
- Check fuel lines and their connections for leaks.
- Replace fuel filter with integrated fuel pressure regulator.
- If the fuel filter is OK, replace fuel pump.

Assembly is in reverse order of removal, note the following:







- Switch off ignition.

NOTE: Before disconnecting pressure gauge, release pressure by opening shut-off valve. Hold collecting container in front of hose.

- Tighten fuel supply line (ensure cleanliness).

Torque specifications
Fuel line to fuel rail 22 Nm