Fuel Pressure: Testing and Inspection

Fuel Pressure and Residual Pressure before High Pressure Pump, Checking

Special tools, testers and auxiliary items required

• Pressure gauge K-Jetronic (V.A.G 1318)

• Pressure gauge adapter (V.A.G 1318/10-12)

• 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 1 of right fuse panel in center bracket of instrument panel - 2 - is OK.





• Fuel Pump (FP) Control Module (J538) OK; check in "Guided Fault Finding" with Vehicle Diagnosis, Testing and Information System (VAS 5051B).

• Fuel filter OK.

• Fuel tank at least 1/4 filled.

• Ignition switched off.

Fuel Pressure, Checking

- Remove rear seat bench.

- Remove cover for right locking flange - arrows -.





- Disconnect electrical harness connector - arrow - at locking flange.





- Connect Remote Control (V.A.G 1348/3A) with adapter cable (V.A.G 1348/3-3) with an adapter cable from Connector Test Set (V.A.G 1594C) at terminal - 1 -.





- Cover 2nd connector terminal of adapter cable (V.A.G 1348/3-3) with insulating tape to prevent short circuit - arrow -.

- Route Remote Control (V.A.G 1348/3A) switch forward in engine compartment.

- Release the retaining clip and open the cover - A - over the positive terminal clamp.

- Connect alligator clip to the positive terminal clamp.

- Connect contact - 5 - to vehicle Ground (GND) using a jumper cable from the connector test set (V.A.G 1594C).

- Remove fuel filler cap from fuel filler tube.

- Remove rear engine cover - 2 - - arrows -.





• Ignore - 1 -.

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 line - arrow - on fuel rail.





CAUTION!
Note rules of cleanliness for working on the fuel injection system.

- Connect Fuel Inj. Pressure Gauge-CIS (V.A.G 1318) with Adapter (V.A.G 1318/11) and (V.A.G 1318/12) in fuel line.





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

- Open pressure gauge shut-off valve. Shut-off valve faces in direction of flow.

- Bleed fuel system by pressing remote control briefly.

- Close pressure gauge shut-off valve. Shut-off valve is perpendicular to direction of flow.

- Press remote control switch until pressure gauge no longer shows pressure increasing.

• Specified value: Approximately 6 bar (5 to 7 bar) positive pressure.

If specification is not obtained:

- Check delivery quantity of Fuel Pumps (FP).

Residual Pressure, Checking

- Check for leaks and residual pressure by observing pressure drop on Fuel Inj. Pressure Gauge-CIS K-Jetronic (V.A.G 1318).

• After 10 minutes there must be a residual pressure of at least 3.75 bar.

If residual pressure drops below 3.75 bar:

• Check connection between Fuel Inj. Pressure Gauge-CIS K-Jetronic (V.A.G 1318) 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. Then repeat test.

• Replace right Fuel Pump (FP) (G23) if necessary.

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

- Switch off ignition.

• Before disconnecting pressure gauge, release pressure by opening shut-off valve. Hold assisting hose in a container.





- Re-install fuel supply line (ensure cleanliness).

Tightening Specifications