Audi Workshop Service and Repair Manuals

Note:

Fuel pressure regulator regulates fuel pressure as a function of intake pressure. As a result, the pressure drop at the injectors remains constant for each engine speed and load range.

Special tools and workshop equipment required

• ◆ V.A.G 1318
• ◆ V.A.G 1318 with V.A.G 1318/11, V.A.G 1318/12 and V.A.G 1318/13

Test requirements:

• ● Fuel pump relay OK; checking =>Page 24-55.
• ● Fuel pump OK; checking:

=> Fuel Supply - Petrol Engines; Repair group 20

• ● Fuel filter OK
• ● Battery voltage at least 12.7 V
• ● Vehicles with automatic gearbox: Selector lever in position P or N

Check system pressure

• ‒ Briefly open the fuel tank filler cap (to release pressure).

• ‒ → Remove engine cover -arrows-.

• ‒ → Open the screw connection -arrow- and catch escaping fuel in a cloth.
• ‒ Connect pressure gauge V.A.G 1318 to fuel supply pipe using adapters 1318/11, 1318/12 and 1318/13.

• ‒ → Open cut-off 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 value: approx. 3.5 bars

• ‒ → Pull vacuum hose off fuel pressure regulator.
• ‒ The fuel pressure should rise to approx. 4.0 bars.
• ‒ Switch ignition off.
• ‒ Check leak tightness and holding pressure by watching the gauge indicator fall.
• ‒ After 10 minutes the remaining pressure should be at least 2.5 bar excess pressure

If the holding pressure drops below 2.5 bars:

• ‒ 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 -arrow-).
• ‒ Observe pressure drop on gauge.

If the pressure now does not drop:

• ‒ Check fuel pump non return valve.

If the pressure drops again:

• ‒ Open cut-off valve on pressure gauge. The lever points in the 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 now 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.