With Generic Scan Tool

Fuel pressure regulator and residual pressure, checking

Function
The fuel pressure regulator controls the fuel pressure as a function of the Manifold Absolute Pressure (MAP).
The specified value for this test is dependent on the working pressure of the Fuel Pump (FP). This is about 4.0 bar positive pressure

Recommended special tools and equipment





- V.A.G 1318 Pressure gauge
- V.A.G 1318/7 Adapter
- V.A.G 1318/10 Adapter
- V.A.G 1318/13 Hose adapter

Test requirement
- Delivery quantity of Fuel Pump (FP) OK, Fuel Pump (FP), checking. [1][2]Testing and Inspection

Test sequence

WARNING: Fuel system is under pressure! Before opening system, place rags around the connection point. Then release pressure by carefully loosening connection.






- Unscrew fuel supply hose -1- from fuel rail -2-.
- Connect V.A.G 1318 pressure gauge using adapters V.A.G 1318/7, /10 and /13.
- Open shut-off valve of pressure gauge. The lever points in the direction of flow (arrow).
- Start engine and let run at idle.
- Measure fuel pressure.
Specified value: about 3.5 bar positive pressure






- Disconnect vacuum hose from fuel pressure regulator (arrow). Fuel pressure should rise to about 4.0 bar positive pressure.

NOTE: If fuel should escape at the vacuum connection of the pressure regulator, replace pressure regulator.

- Switch ignition off.
- Check for proper seal and residual pressure by observing pressure drop on pressure gauge. After 10 minutes at least 2.2 bar over pressure should still be present.

If residual pressure falls below 2 bar positive pressure:

- Start engine and let run at idle.






- Wait until pressure has dropped, and then switch off ignition. Simultaneously close shut-off valve of V.A.G 1318 pressure gauge (lever perpendicular to direction of flow -arrow-).
- Observe pressure drop on pressure gauge.

If pressure does not drop:
- Test check-valve of Fuel Pump (FP), Fuel Pump (FP), checking. [1][2]Testing and Inspection

If pressure does drop again:






- Open stop valve of pressure gauge V.A.G 1318 (lever in direction of flow -arrow-).
- Start engine and let run at idle.
- Wait until pressure has dropped, and then switch off ignition. Simultaneously pinch return hose -3- tightly together.

If pressure does not drop:
- Replace fuel pressure regulator, item 5 .

If pressure does drop again:
- Check whether line connections, O-rings in fuel rail, and fuel injectors are properly sealed.
- Check whether pressure gauge is properly sealed.

NOTE: Before removing pressure gauge, put cleaning rags back around line connection which is to be disconnected.