Fuel Pressure Test

Diagnostic Procedures

Fuel Pressure Test

Special tools, testers and auxiliary items required

• Multimeter.

• fuel line adapter set (V.A.G. 1318/17A). These tools may be substituted with an equivalent aftermarket tool and are also available for rental or purchase through Volkswagen.

• In line Fuel pressure gauge with shutoff valve. (high pressure).

Test conditions

• Battery voltage 12.5 V

• Function and voltage supply for the Fuel Pump is OK.

• Fuel tank at least 1/4 filled.

• Ignition switched off.

Test procedure

- Observe safety precautions. Refer to => [ Safety Precautions ] Safety Precautions

- Observe Clean Working Conditions. Refer to => [ Clean Working Conditions ] Clean Working Conditions

- Perform a preliminary check to verify the customers complaint. Refer to => [ Preliminary Check ] Preliminary Check.

CAUTION!
Fuel supply line is under high pressure! Wear protective goggles and protective clothing to prevent injuries and contact with skin. Before removing from hose connection consult the Repair Information for proper procedure.

- Remove high pressure in fuel system.

- Place a cloth around connection and slowly loosen union nut - arrow - to reduce fuel pressure.





- Then tighten threaded connection again.

- Connect a pressure gauge with the appropriate adapter, as shown.

- Make sure hose clamps are seated securely.





- Open shut off valve of pressure gauge. The lever points in the direction of flow.





- Remove nuts - 1 - on right side of fuel delivery unit cover. If necessary, remove backrest support - 2 - or mounting bracket: refer to the Repair Information.





- Disconnect connector from Fuel Pump Control Module (J538) - 5 -.

- Disconnect harness connector - 3 - from flange assembly of fuel delivery unit.





- Connect hand held remote starter (jumper) with adapter cables from connector test kit to terminal - 1(+) - of Fuel Pump and to terminal - 3(+) - of harness connector of Fuel Pump Control Module (J538).

- Connect terminals - 4(-) - of harness connector and - 4(-) - of Fuel Pump using an adapter cable from connector test kit.

- Switch ignition on.

- Operate hand held remote starter (jumper) and observe display of pressure gauge while doing this.

Fuel pressure must increase up to a maximum pressure of 6 bar.

• When releasing control button of the hand held remote starter (jumper), fuel pressure decreases to approx. 5.6 bar.

If fuel pressure is OK, perform a Residual Pressure check.

If specification is exceeded:

- Pressure relief valve in flange assembly is faulty, replace sender assembly. Refer to the Repair Information.

If specification is not obtained:

- Check fuel lines for possible restrictions (kinks) or blockages.

- Check all fuel lines in fuel tank for leaks.

- Check fuel filter for leaks.

If no malfunction can be found:

- Replace flange assembly with pressure relief valve. Refer to the Repair Information.

- Repeat test.

If fuel pressure is not obtained again:

- Fuel Pump faulty, replace fuel delivery unit. Refer to the Repair Information.