Fuel Pressure: Testing and Inspection

The Fuel Pressure Regulator Controls Fuel Pressure Relative To Manifold Absolute Pressure.

Special tools, testers and auxiliary items
- VAG 1318 Pressure tester
- 1318/10 Adaptor
- VAG 1318/1 Hose

Requirement:
- 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 adaptor with VAG 1318/1 hose.
- Close pressure gauge shut-off,
- lever must be perpendicular to 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 OFF ignition.
- 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 OFF ignition.
- Immediately thereafter, clamp 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 while doing this.