With Manufacturer's Scan Tool

Checking Fuel Pressure Regulator And Holding Pressure

Engine codes AVH, AZG
The fuel pressure regulator regulates the fuel pressure depending on intake manifold pressure.

- Pressure tester V.A.G1318
- Adapter V.A.G 1318/10
- Adapter V.A.G1318/11
- Hose adapter VA.G 1318/16
- Hose clamp pliers VA.G 1921

Work sequence

- Remove fuse No. 28 (fuel pump) from fuse holder.

CAUTION: 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 -1 - and collect leaking fuel with a cloth.

- Connect pressure gauge V.A.G1318 to fuel supply line and to fuel rail with adapters V.A.G 1318/10, V.A.G 1318/11 and hose adapter V.A.G 1318/16.
- Open shut-off tap on pressure gauge. Lever points in direction of flow - arrow -.
- Refit 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 -.
- 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 off ignition.
- 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.

- Open shut-off tap on pressure tester V.A.G1318 (handle points in direction of flow - arrow -).
- Start engine and run at idling speed.
- Switch ignition off after pressure has build-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 rail and injectors for leaks.
- Check pressure gauge for leaks.

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

Engine codes BEV, BGD
The fuel pressure regulator regulates the fuel pressure to approx. 4 bar.

The fuel pressure regulator is located on the fuel filter.

Special tools, testers and auxiliary items required
- Pressure tester V.A.G 1318
- Adapter V.A.G 1318/9
- Adapter V.A.G 1318/17
- Adapter V.A.G 1318/23
- Remote control V.A.G 1348/3A with adapter cable V.A.G 1348/3-2

Work sequence

- Pull off fuel supply line on connection -1 - and collect leaking fuel with a cloth.

NOTE: To do this slide securing ring -2-in connection -1 -.

- Connect pressure gauge V.A.G1318 to fuel supply line and to fuel rail with adapters V.A.G 1318/9 and V.A.G 1318/17.
- Open shut-off tap on pressure gauge. Lever points in through-flow direction (position - A -).
- Refit fuse 28 (fuel pump) in fuse holder.
- Start engine and run at idling speed.
- Measure fuel pressure.
- Specification: approx. 4 bar

If the specification is not obtained:
- Switch off ignition.
- Check that fuel pump can create and maintain this pressure, Checking fuel pump non-return valve.
- Check fuel pressure regulator.

If the specification is obtained:
- Switch off ignition.
- Check for leaks and holding pressure (entire system) 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 tester V.A.G1318 shut-off tap (handle at right angles to through-flow direction - arrow -).
- Observe pressure drop on pressure gauge (engine side).

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

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

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

Checking fuel pressure regulator

Requirements
- Fuel pump non-return valve OK, checking
- Fuel supply line OK

Work sequence

- Pull fuse No. 28 out of fuse holder.
- Connect remote control V.A.G1348/3A with adapter cable V.A.G1348/3-2 to contact 28a to fuel pump and battery positive (+)

- Pull supply hose -1 - off fuel filter outlet.

NOTE: Press locking ring inward to release fuel lines.

- Connect pressure gauge V.A.G1318 to fuel filter outlet with adapters V.A.G 1318/23 and V.A.G 1318/17.
- Close pressure gauge shut-off tap (lever at right angles to through flow direction - position - B -).
- Operate remote control V.A.G1348/3A for approx. 10 seconds to fill fuel filter and to build up a system pressure of approx. 4 bar.
- Observe pressure drop on gauge.
- After 30 minutes, pressure must not drop below 3.2 bar.

If the pressure drops further:
- Check line connections for leaks.

If no fault in lines is detected:
- Replace fuel pressure regulator.