Fuel Pump (FP) check-valve, checking

WARNING: This page is about a different car, the 2004 Volkswagen R32. However, it is still accessible from the selected car via links, so may be relevant.

Test conditions

Remote control for VAG 1348 V.A.G 1348/3A is still connected.

Pressure gauge V.A.G 1318 is still connected.

Test sequence

NOTE:

This test also checks the connections of the fuel supply line from fuel delivery unit to connection point of pressure gauge V.A.G 1318 for proper seal.

Fig 1: Locating V.A.G 1318 Shut-Off Tap

Courtesy of VOLKSWAGEN UNITED STATES, INC.

Close pressure gauge V.A.G 1318 shut-off tap (lever at right angle to direction of flow).
Operate remote control V.A.G 1348/3A at short intervals, until a pressure of approx. 3 bar has built up.

CAUTION: Danger of fuel spray when opening shut-off tap; Wear protective eyewear and clothing to prevent injuries and skin contact with fuel. Hold a container in front of the open connection of the pressure gauge.

If pressure builds up too high, lower excess pressure by carefully opening the shut-off tap.
Watch pressure drop on gauge. After 10 minutes the pressure must not drop below a 2.5 bar decrease.

If pressure drops further:

Check line connections for leaks.

If no fault is detected in wiring:

Fuel Pump (FP) faulty, replace fuel delivery unit, refer to Fuel delivery unit, removing and installing .