Audi Workshop Service and Repair Manuals

Note:

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

Test conditions

• ● Fuel pump relay OK; testing .
• ● Fuel pump OK
• ● Fuel filter OK
• ● Battery voltage OK.

Special tools, testers and auxiliary items

• ◆ Pressure tester V.A.G 1318
• ◆ Adapter 1318/8
• ◆ Adapter 1318/9
• ◆ Adapter 1318/17

• ‒ 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 (valve handle points in 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 increase 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 (valve handle 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 handle 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 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 fuel pressure by opening the cut-off tap. When doing this hold a container over the connection.