Fuel Pressure Regulator: Testing and Inspection
Fuel pressure regulator and residual pressure, checkingWARNING: Fire hazard. Do NOT smoke or have anything in area that can ignite fuel!
CAUTION: Fuel under pressure! Cover the fuel rail test measuring point with a rag to protect against fuel spray when removing the sealing screw.
- connect VAG 1318 pressure tester to fuel rail using adaptor VAG 1318/10
NOTE: Shut-off valve for VAG 1318 pressure tester must be closed. The lever (arrow) must be perpendicular to the direction of flow.
- start engine and let idle
- observe fuel pressure on gauge
- must be approx. 3.5 bar gauge pressure
- disconnect hose from fuel pressure regulator (arrow)
- fuel pressure must increase to approx. 4.0 bar gauge pressure, after 10 minutes gauge pressure must not be less than 2.5 bar
If after 10 minutes gauge pressure is less than 2.5 bar
- check for leaks in system
- start engine and after fuel pressure builds up, switch OFF ignition
- at same time, clamp blue return line tightly and observe pressure drop on pressure gauge
If pressure does NOT drop
- fuel pressure regulator is defective
If pressure drops again
- check if:
- line connectors are tight
- 0-rings or seals on fuel distributor leak
- fuel injectors leak
- fuel pump check valve leaks
- VAG 1318 Pressure tester leaks (at shut-off valve)
NOTE: Drain any residual fuel from the pressure tester before disconnecting it from the fuel rail.