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 approx. 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 adapter

Test requirement
- Delivery quantity of Fuel Pump (FP) OK, check. Fuel Pump (FP), checking. Fuel Pump, Checking - I

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: approx. 3.5 bar positive pressure







- Disconnect vacuum hose from fuel pressure regulator (arrow). Fuel pressure should rise to approx. 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 positive pressure still be present.

If residual pressure falls below 2 bar positive pressure:
- Start engine and let run at idle.







- Wait until pressure has built up, 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. Fuel Pump, Checking - I
If pressure drops 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 built up, and then switch off ignition. Simultaneously pinch return hose -3- tightly together.

If pressure does not drop:
- Replace fuel pressure regulator.

If pressure drops again:
- Check whether line connections, O-rings in fuel rail, and fuel injectors are properly sealed.
- Check pressure gauge for proper seal.

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