A8 Quattro Sedan V8-4.2L (AUX) (2001)
-
Pull vacuum hose -arrow- off fuel pressure regulator.
NOTE: If fuel flows out at the vacuum connection on the fuel pressure regulator during the following pressure test, install a new fuel pressure regulator.
The fuel pressure must increase to approx. 4.0 bar.
If specification is not obtained:
-
Install new pressure regulator as a trial measure and repeat the pressure test.
-
If fuel pressure still does not match specification, check fuel pump and supply line for damage (e.g. pinching) and replace if necessary.
If specification is obtained:
-
Reconnect vacuum hose.
-
Switch ignition off.
-
Observe pressure drop on pressure gauge to check leakage and residual pressure.
After 10 minutes the pressure should still be at least 3 bar.
If holding pressure drops below 3.0 bar:
-
Start engine and run at idle speed.
-
Switch ignition off after pressure has built up. At the same time close cut-off valve on VAG1318 pressure gauge (valve handle at 90° to direction
of flow).
-
Observe pressure drop on gauge.
If the pressure drops again, the following malfunctions are possible:
-
Connections on pressure gauge downstream of cut-off valve leaking
-
Fuel pressure regulator defective
-
Injectors leaking
If the pressure does not drop, the following malfunctions are possible: