Fuel Pressure Regulator: Testing and Inspection

Fuel Pressure Regulator And Holding Pressure, Checking

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





Special tools and equipment
- VAG 1318 Pressure gauge
- 1318/10 Adapter
- 1318/11 Adapter
- 1318/16 Adapter

Test conditions
- Fuel pump delivery rate OK, checking

Test sequence

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 fuel pump fuse No. 40 out of fuse holder.







- Pull off supply pipe/hose -1- and collect leaking fuel with a cloth.
- Connect pressure gauge VAG 1318 using adapters VAG 1318/10,/11 and /16.
- Open measured device cut-off tap. (handle points in through-flow direction -arrow-).
- Reinsert fuse 28 (fuel pump) into fuse holder.
- Start engine and run at idle speed.
- Check fuel pressure.
Specification: Approx. 2.5 bar

If the specification is obtained:







- Pull vacuum hose -1- off connection -2-. Fuel pressure must increase to: approx. 3.0 bar.
- 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 idle speed.







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

If the pressure drops again:
- Check fuel pump non-return valve.

If the pressure does not drop:







- Open pressure tester VAG 1318 shut-off tap (handle in through-flow direction).
- Start engine and run at idle 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, item 22.

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.