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

• Adapters (VAG 1318/10-12)

• Connector test set (VAG 1594C)

• Fuel injector pressure gauge (VAG 1318)

• Remote control (VAG 1348/3A) with remote control for VAG 1348 (VAG 1348/3-3)

• Measuring container, fuel resistant

• Protective gloves

Fuel Pressure, Checking

• Battery voltage at least 12.5 volts.

• Fuel filter OK.

• Fuel tank at least 1/4 filled.

• Fuel pump control module OK

• Ignition switched off.

- Remove the right luggage compartment side trim cover - arrows -.





- Remove the positive terminal cover - 2 - on the battery.





• Ignore - item 1 -.

- Remove the luggage compartment floor mat trim.





- Remove the left locking flange cover bolts - arrows - and cover.

- Disconnect the electrical connector - 2 - from the left locking flange.





• Ignore - item 1 -.

- Remove the right locking flange cover bolts - arrows - and cover.





- Disconnect the electrical connector - 2 - from the right locking flange.





• Ignore - item 1 -.

- Connect the (VAG 1348/3A) with (VAG 1348/3-3) and a adapter cable from (VAG 1594C) to terminal - 4 - (ground) on the left and right locking flanges.





- Route the (VAG 1348/3A) switch forward into the engine compartment.

- Connect the alligator clip to the ground point in the engine compartment.

- Connect terminal - 1 - (positive) on the left and right locking flanges using a self made adapter cable to the vehicles positive battery terminal. For safety reasons, install a fuse - A - (10 A) in the wiring.





- Remove the fuel filler cap from the fuel filler tube.

- Remove the rear engine cover.

Disconnect the fuel supply line - arrow - on the distribution piece (with magnesium intake manifolds)





Disconnect the fuel supply line - arrow - on the distribution piece (with plastic intake manifolds)





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

- Connect the (VAG 1318) with adapter and (VAG 1318/10-12) in fuel line.





- Attach an assisting hose to the (VAG 1318) and hold it in a container.

- Open the shut off lever on the (VAG 1318).

• The lever points in the direction of flow.

- Bleed the fuel system by pressing the (VAG 1348/3A) briefly.

- Close the shut off valve on the (VAG 1318).





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

- Hold the switch for the (VAG 1348/3A) until no more pressure increase is observed on the (VAG 1318).

• Specified value: approximately 5.5 bar (4.5 to 6.5 bar) positive pressure

If the specification is not obtained:

- Check the fuel delivery quantity of the individual fuel pumps.

Checking Residual Pressure

- Check for leaks and residual pressure by observing the pressure drop on the (VAG 1318).

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

If the residual pressure drops below 3 bar:

• Check the connection between the (VAG 1318) and fuel line for leaks.

• Check the (VAG 1318) for leaks.

• Check the fuel lines and their connections for leaks.

• Check the fuel delivery quantity of the individual fuel pumps.

• Replace the fuel filter with integrated fuel pressure regulator.

• The check valve in one of the two fuel pumps is faulty.

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

- Switch off the ignition.

• Before removing the (VAG 1318), release the fuel pressure by opening shut off lever. Hold a container under the connection.

- Attach the fuel supply line on the distribution piece.