Audi Workshop Service and Repair Manuals

Test conditions

• ● Fuel pump relay OK, testing =>Page 24-30.
• ● Fuel pump OK
• ● Fuel filter OK
• ● Battery voltage OK

Note:

The fuel pressure regulator regulates the fuel pressure according to the intake manifold pressure at the throttle valve unit.

• ‒ Pull fuel supply hose (white marking) off fuel supply pipe.
• ‒ Connect pressure gauge V.A.G 1318 to fuel supply pipe using adapters 1318/8, 1318/9 and 1318/17.
• ‒ → Open cut-off valve on pressure gauge. The lever points in the direction of flow.
• ‒ Start the engine and run at idling speed.
• ‒ Measure fuel pressure.

Specification: approx. 2.5 bar

• ‒ → Pull vacuum hose off fuel pressure regulator. The fuel pressure should rise to approx. 3.0 bar.
• ‒ Switch off ignition.
• ‒ Check leak tightness and holding pressure by watching the gauge indicator fall. After 10 minutes the remaining pressure should be at least 1.5 bar.

If the holding pressure drops below 1.5 bar:

• ‒ Start the engine and run at idling speed.
• ‒ → Allow the pressure to build up, then switch off the ignition. At the same time close the cut off valve on the pressure gauge V.A.G 1318 (valve lever at right angles to direction of flow).
• ‒ Observe pressure drop on gauge.

If the pressure does not drop:

• ‒ Check fuel pump non return valve.

If the pressure drops again:

• ‒ → Open cut off valve on pressure gauge V.A.G 1318 (valve lever points in direction of flow).
• ‒ Start the engine and run at idling speed.
• ‒ Allow the pressure to build up, then switch off the ignition. At the same time pinch the return hose (with blue marking) firmly together.

If the pressure does not drop:

• ‒ Renew the fuel pressure regulator.

If the pressure drops again:

• ‒ Check pipe connections, O-rings on fuel manifold and injectors for leaks.
• ‒ Check pressure gauge for leaks.

Note:

Before removing the pressure gauge, release the fuel pressure by opening the cut off valve. When doing this hold a container over the connection.