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)

• Connector Test Set (V.A.G 1594C)

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

• Measuring container, fuel-resistant

Test Conditions

• Battery voltage at least 12.5 Volts

• Fuel filter OK.

• Fuel tank minimum 1/4 full.

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

• Ignition turned off

Fuel Pressure, Checking

- Remove rear seat bench.

- Remove the cover from the locking flange - arrows -.






- Disconnect electrical harness connector - 1 - at locking flange.






• Ignore - 2 -.

- Connect the (V.A.G 1348/3A) with (V.A.G 1348/3-3) with an adapter cable from the (V.A.G 1594C) at terminal - 1 -.

- Using insulating tape, tape over the second terminal on the (V.A.G 1348/3-3) - arrow - to prevent a short circuit.






- Connect terminal - 5 - to the vehicle ground using a jumper cable from the (V.A.G 1594C).

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

- Remove the seal - arrow -.






- Unclip the plenum chamber cover - 2 - and remove it.

• Ignore - 1 and 3 -.

- Release the retainer - arrow A - and open the cover - arrow B -.






- Connect the (V.A.G 1348/3A) to - A - in the terminal box inside the plenum chamber (battery positive). For safety reasons, install a fuse (10 A) in the wiring connection.






- Remove the bolts - arrows -, remove the air guides - 1 and 2 -.






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

• The fuel pressure must be reduced to residual pressure before opening the high pressure area of the fuel injection system. Refer to => [ Releasing Pressure in High Pressure Area ] Releasing Pressure In High Pressure Area.

- Reduce fuel pressure in high pressure area. Refer to => [ Releasing Pressure in High Pressure Area ] Releasing Pressure In High Pressure Area.

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






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






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

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

• The lever points in the direction of flow.

- Bleed the fuel system by briefly pressing the 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

- 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 pressure gauge for leaks.

• Check fuel lines and their connections for leaks.

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

• Fuel pump check-valve is faulty.

Assembling

Assemble in reverse order of disassembling. Note 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 under the connection.

- Connect the fuel supply hose - arrow - to the high pressure pump. Make sure the hose is clean.






• Tightening Specifications: High pressure pump assembly overview, refer to => [ High Pressure Pump Overview ] High Pressure Pump Overview

- Install the rear bench seat.

• Check fuel system for leaks.