With Manufacturer's Scan Tool

Fuel pressure, fuel pressure regulator and residual fuel pressure, checking

WARNING! Fire hazard! Do not smoke, work near heaters or open flame, or have anything nearby that could ignite fuel. The fuel system is under pressure. Before opening, cover connections with a rag, and open carefully to release pressure.

The fuel pressure regulator controls the fuel pressure depending on intake manifold pressure.

Special tools and equipment
- Pressure tester VAG1318
- Adapter 1318/7
- Adapter 1318/10
- Adapter 1318/13

Checking requirements
- Fuel pump delivery rate OK; checking:
- Pressure tester VAG1318 must be installed with the shut-off valve between the fuel supply line and the gauge for proper evaluation of residual pressure tests.

Checking






- Disconnect fuel supply hose -1- from fuel rail -2-.
- Connect pressure tester VAG1318 using adapters 1318/7,1318/10 and 1318/13.
- Open shut-off valve on pressure tester (arrow).
The lever is parallel to direction of flow.
- Start engine and let idle.
- Measure fuel pressure.
Specified value: approx. 3.5 bar (51.45 psi)

If the specification is attained:






- Disconnect vacuum hose from fuel pressure regulator (arrow).
The fuel pressure must increase to approx. 4.0 bar (58.8 psi).

- Switch ignition off.

- Check for leaks and residual pressure by observing pressure drop on gauge.
After 10 minutes there must be a residual pressure of at least 2.0 bar (29.4 psi).

If the residual pressure drops below 2 bar (29.4 psi):
- Start engine and let idle.
- Switch ignition off after pressure has built- up.






- Close shut off valve on VAG1318 pressure tester.
The lever is perpendicular to direction of flow.

- Observe pressure drop on gauge.

If the pressure does not drop:
- Check the check valve in electric fuel pump.

If the pressure drops again:






- Open shut-off valve on pressure tester (arrow).
The lever is parallel to direction of flow.

- Start engine and run at idle.
- Switch ignition off after pressure build-up.
- At same time pinch/seal return hose -3- together.

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

If the pressure drops again:
- Check pipe connections, O-rings on fuel rail and fuel injectors for leaks.
- Check pressure gauge for leaks.

NOTE: Before removing pressure gauge place a cloth around the connections to be loosened.