Fuel Pressure, Checking

Fuel Pump, Checking

Special tools, testers and auxiliary items required

• Pressure Tester (VAS 6550)

• Remote Control (V.A.G 1348/3A)

• Test Instrument Adapter/DSO (5 pin) (VAS 5565)

• Multi-Meter (V.A.G 1715)

• Wrench (T10202)

• Measuring Container, 2 Liter

Fuel Pressure, Checking

Conditions

• The fuel pump function must be checked. Refer to => [ Function and Voltage Supply, Checking ]. Function and Voltage Supply, Checking

Sequence

Read the safety precautions before beginning work. Refer to => [ Safety Precautions ] Fuel Supply.

- Observe the rules for cleanliness. Refer to => [ Clean Working Conditions ] Fuel Supply.

CAUTION!
The fuel supply line is under pressure! Wear protective goggles and protective clothing to prevent injuries and contact with skin. Before disconnecting the connection, wrap a cloth around the connection. Carefully disconnect the connection to release the pressure.

- Disconnect the supply line (metal coupling) - arrow - and collect any leaking fuel with a cloth.





• Press in the securing ring to disengage the fuel line.

- Connect the (VAS 6550) to the fuel supply line using (VAS 6550/1) and (VAS 6550/2).





- Make sure the drain valve lever - C - is closed and levers - A and B - are open.





- Activate the fuel pump with output Diagnostic Test Mode (DTM) to build fuel pressure.

- Check the fuel pressure on the (VAS 6550).

• Specified value: 4.0 to 7.0 bar.

If fuel pressure is OK, check the residual pressure. Refer to => [ Residual Pressure, Checking ]. Residual Pressure, Checking

If the Specification is Exceeded

- If the pressure relief valve in the fuel filter is faulty, then replace the flange with fuel filter:

Front Wheel Drive (FWD), refer to - item 20 -=> [ Flange with Fuel Filter ] Fuel Tank and Components Overview.

All Wheel Drive (AWD), refer to - item 22 -=> [ Flange with Fuel Filter ] Fuel Tank and Components Overview.

If the Specification is not Obtained

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

If no malfunction can be found:

- Replace the flange with fuel filter and pressure relief valve, refer to one of the following:

FWD, refer to - item 20 -=> [ Flange with Fuel Filter ] Fuel Tank and Components Overview.

AWD, refer to - item 22 -=> [ Flange with Fuel Filter ] Fuel Tank and Components Overview.

- Repeat the test.

If the Specification is Again not Obtained

- Replace the fuel delivery unit if the fuel pump is faulty. Refer to => [ Fuel Delivery Unit ] Fuel Delivery Unit.