A8 Sedan V8-3.7L (AEW) (1997)
-
Disconnect vacuum hose (arrow) for fuel pressure regulator.
-
Fuel pressure must increase to approx. 4.2 bar (61 psi).
-
Switch ignition off.
-
Check residual pressure by observing pressure reduction.
After 10 minutes at least 3 bar (44 psi) pressure must still be indicated on gauge.
If residual pressure drops below 3.0 bar (44 psi):
-
Start engine and stop engine after fuel pressure has built up.
-
Close valve on fuel pressure gauge VAG1318.
If residual fuel pressure holds:
-
Connection between fuel pressure gauge and fuel pressure regulator leaking.
-
Fuel pressure regulator leaking; replace if necessary.
-
Fuel injectors leaking. Refer "Fuel injector","Fuel Injection Volume, Fuel Injector Leakage and Spray Pattern, Checking" See: Powertrain
Management/Fuel Delivery and Air Induction/Fuel Injector/Testing and Inspection
If residual fuel pressure drops again:
-
Connection between fuel pressure gauge and fuel supply line leaking.
-
Fuel supply line at fuel tank leaking.
-
Check valve in fuel pump leaking.
NOTE: Before disconnecting the fuel pressure gauge, close the valve, disconnect line at VAG1318/12 adapter, and pour left-over fuel into suitable
container by opening valve.