With Manufacturer's Scan Tool

Fuel Pressure Regulator And Holding Pressure, Checking
The fuel pressure regulator controls the fuel pressure dependent upon intake manifold pressure.







Special tools and equipment
- V.A.G1318 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 line/hose -1- and collect leaking fuel with a cloth.







- Connect V.A.G1318 pressure gauge to fuel supply line/hose and to hose to fuel rail using adapters 1318/9 and 1318/17.
- Open shut-off tap on pressure gauge. Handle points in direction of flow.
- Reinstall fuse 28 (fuel pump) in fuse holder.
- Start engine and run at idling speed.
- Measure fuel pressure.
Specification: Approx. 2.5 bar







- Pull vacuum hose -1- off fuel pressure regulator -2-.
Specification: 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 engine and run at idling speed.







- Switch ignition off after pressure has built-up. At same time close pressure measured device cut-off tap (handle across 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 V.A.G1318 pressure tester shut-off tap (handle in through-flow direction).
- Start engine and run at idling speed.
- Switch ignition off after pressure has built-up. At same time pinch/seal return hose together.

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

If the pressure drops again:
- Check line 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.