With Manufacturer's Scan Tool

Fuel Pressure Regulator And Holding Pressure, Checking






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

Special tools, test equipment and auxiliary items
- V.A.G 1318 Pressure gauge
- 1318/9 Adapter
- 1318/17 Adapter

Test sequence






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

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






- Connect pressure gauge V.A.G 1318 to fuel supply pipe/hose and to hose to fuel rail using adapters 1318/9 and 1318/17.
- Open measured device cut-off tap. (The handle points in through-flow direction - arrow-).
- Start the engine and run at idle speed.
- Measure fuel pressure.
Specification: Approx. 2.5 bar

If the specification is obtained:






- Pull vacuum hose off fuel pressure regulator -arrow-. The fuel pressure must increase to approx. 3.0 bar.
- Switch off ignition.

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

If the specification is obtained:
- 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 idle 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 does not drop:






- Open pressure tester V.A.G 1318 shut-off tap (handle in through-flow direction).
- Start the engine and run at idle 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, item 4.

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 pressure gauge place a cloth around the connections to be loosened.