Audi Workshop Service and Repair Manuals

Test conditions

• ● Fuel pump relay OK, testing =>Page 24-28.
• ● Fuel pump OK.
• ● Fuel filter OK.
• ● Battery voltage OK.

Note:

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

• ‒ Briefly open the fuel tank filler cap (to release pressure).
• ‒ Cover the pressurised screw connection with a cloth.

• ‒ → Open the screw connection -arrow- and catch the emerging fuel with a cloth.

• ‒ Connect pressure gauge V.A.G 1318 to fuel supply pipe using adapters 1318/11, 1318/12 and 1318/13.
• ‒ → Open isolating valve on pressure gauge. The lever points in the direction of flow.
• ‒ Start the engine and run at idling speed.
• ‒ Measure the fuel pressure.

• Specified result: approx. 3.5 bar gauge.

• ‒ → Pull vacuum hose -arrow- from fuel pressure regulator.

• The fuel pressure must rise to approx. 4.0 bar gauge.

• ‒ Put the vacuum hose back on.
• ‒ Switch off ignition.
• ‒ Observe the pressure drop on the gauge.

• After 10 minutes the remaining pressure should be at least 2.5 bar.

If the pressure held drops below 2.5 bar:

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

If the pressure does not drop, the following faults are possible:

• ◆ Fuel pressure regulator defective
• ◆ Injectors leaking
• ◆ Screw connections of the pressure gauge after the isolation valve leaking

If the pressure drops again, the following faults are possible:

• ◆ Screw connection between pressure gauge and fuel supply line leaking
• ◆ Fuel supply line leaking at petrol tank
• ◆ Non-return valve in the fuel pump leaking

=> 4-cylinder engine, mechanical components; Repair Group 20; remove and install fuel pump

Note:

To remove the pressure gauge, close the isolation valve, release the screw connection on the adapter V.A.G 1318/12 and drain excess fuel into the collecting vessel by opening the isolation valve.