Fuel Pressure Regulator and Residual Pressure, Checking

Fuel Pressure Regulator and Residual Pressure, Checking

The fuel pressure regulator controls fuel pressure relative to manifold absolute pressure.

Special tools and equipment
- VAG 1318 Pressure tester
- 1318/10 Adapter
- VAG 1318/1 Hose

Test conditions
- Fuel pump delivery rate OK

Test sequence


CAUTION!
Fuel system is pressurized! Wrap a cloth around the connection before loosening hose connections or opening a test connection. Carefully release pressure by pulling off the hose or by removing the plug.







- Remove plug -1- on fuel pressure regulator bracket.
- Connect VAG 1318 pressure gauge to measuring connection using VAG 1318/10 adapter with VAG 1318/1 hose.
- Close pressure gauge shut-off. The lever must point 90° to direction of flow (arrow).
- Start engine and let idle.
- Measure fuel pressure.
- specification: approx. 2.5 bar







- Pull vacuum hose off fuel pressure regulator (arrow).
- fuel pressure must increase to approx. 3.0 bar
- Switch ignition off.
- Check for leaks and at same time measure residual pressure by watching pressure drop on gauge.
- after 10 minutes residual pressure must be 2 bar minimum

If pressure drops below 2 bar:
- Start engine and let idle.
- After pressure has built-up, switch ignition off. At same time, clamp-off fuel return line (blue markings) positioned on fuel pressure regulator bracket.
- Observe pressure drop on gauge.

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

If pressure drops:
- Check fuel pump check valve.
- Check fuel line connections and O-rings on lower intake manifold and fuel injectors for leaks.
- Check pressure gauge for leaks.


NOTE: Before removing the pressure gauge release any residual fuel pressure by opening the shut-off. Hold a container over the connection during this step.