Fuel Pressure Regulator and Holding Pressure, Checking

Fuel Pressure Regulator and Holding Pressure Check

The fuel pressure regulator controls the fuel pressure dependent upon intake manifold pressure.

Special tools and equipment







- VAG1318 Pressure gauge
- 1318/9 Adapter
- 1318/17 Adapter

Test sequence







- Remove fuse 28 (fuel pump) from fuse holder.


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







- Pull off supply pipe/hose -1- and collect leaking fuel with a cloth.







- Connect VAG1318 pressure gauge to fuel supply pipe/hose and to hose to fuel rail using adapters 1318/9 and 1318/17.
- Open shut-off tap on pressure gauge. The handle points in direction of flow.
- Refit fuse 28 (fuel pump) in fuse holder.
- Start the engine and run at idling speed.
- Measure fuel pressure. Specification: Approx. 2.5 bar







- Pull the vacuum hose -1- off fuel pressure regulator -2-. The fuel pressure must increase to approx. 3.0 bar.

If the specification is not obtained:
- Check quantity supplied by fuel pump.

If the specification is obtained:
- Switch ignition off.
- Check for leaks and holding pressure by observing pressure drop on gauge. After 10 minutes there must be a residual pressure of at least 2.0 bar.

If the holding pressure drops below 2 bar:
- Start the engine and run at idling speed.







- Switch ignition off after the pressure has built-up. At the same time close pressure measured device cut-off tap (handle cross through-flow direction -arrow-).
- Observe pressure drop on gauge.

If the pressure does not drop:
- Check fuel pump non-return valve.

If the pressure drops again:







- Open VAG1318 pressure tester shut-off tap (handle in through-flow direction).
- Start the engine and run at idling speed.
- Switch ignition off after the pressure has built-up. At the same time pinch/seal the return hose together.

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

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


NOTE: Before removing the pressure gauge, remove fuse 28 and place a cloth around the connections to be loosened.