Fuel Pressure Regulator and Residual Pressure, Checking

Fuel Pressure Regulator And Residual Pressure, Checking

The fuel pressure regulator controls the fuel pressure and is dependent on intake manifold pressure.

The specification for the check is dependent upon the working pressure of the fuel pump. This is approx. 4.0 bar positive pressure

Special Tools, Testers, Measuring Instruments and Auxiliary Items







- V.A.G 1318 Pressure gauge







- V.A.G. 1318/6 + 7 adapter







- V.A.G 1318/17 (2x)

CAUTION: Fuel system is under pressure. Before opening the system place a cloth around the connection. Then release pressure by carefully loosening the connection.

Test Sequence







- Remove the engine cover - arrows -.







- Remove screw -1 - and remove cover over reservoir - arrow -.
- Briefly open fuel filler cap (pressure release).







- Disconnect fuel supply line -1 - by pressing release button.







- Connect V.A.G 1318 pressure gauge with adapters 1318/7 and 1318/17 (qty. 2) to supply line.
- Open shut-off tap on pressure gauge. The lever points in direction of flow.
- Start the engine and run at idle speed.
- Measure fuel pressure.
- Specification: approx. 2.5 bar positive pressure







- Disconnect vacuum hose at fuel pressure regulator.
- Fuel pressure must increase to approx. 3.0 bar

- Switch off ignition.
- Check for leaks and for residual pressure by observing the pressure loss on the pressure gauge.
- After 10 minutes there must be a residual pressure of at least 1.5 bar

The residual pressure drops below 1.5 bar:
- Start the engine and run at idle speed.







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

If the pressure does not drop:
- Test check valve of fuel pump.

If the pressure drops again:
- Open shut-off valve of V.A.G 1318 pressure gauge (lever in direction of flow).
- Start the engine and run at idle speed.
- Wait until pressure has built up, then switch off ignition. You must clamp fuel return line (with blue marking) completely closed at the same time.

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

If the pressure drops again:
- Check line connections, O-rings at fuel rail and fuel injectors for proper seal.
- Check pressure gauge for leaks.

NOTE: Before disconnecting pressure gauge, release fuel pressure by opening shut-off valve. Hold a container under the connection.