Fuel Pressure Regulator and Holding Pressure, Checking

Fuel Pressure Regulator And Holding Pressure, Checking (Engine codes BBW, BEV)

NOTE:
- The fuel pressure regulator regulates the fuel pressure to approx. 4 bar.
- The fuel pressure regulator is located at the fuel filter (in the fuel tank).

Special tools and equipment







- V.A.G 1318 Pressure gauge
- 1318/9 Adapter
- 1318/17 Adapter
- 1318/23 Adapter
- V.A.G 1348/3 A Remote control

Work sequence
- Remove cover in front of fuse holder.







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

WARNING: The fuel system is under pressure. Before opening the system place a cloth around the connection. Then release the pressure by carefully loosening the connection.







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

NOTE: To disconnect line slide safety ring -2- into the union -1-.







- Connect pressure gauge V.A.G 1318, as shown, with adapters 1318/9 and 1318/17.
- Open shut-off tap on pressure gauge. Handle points in direction of flow.
- Refit fuse 28 (fuel pump) in fuse holder.
- Start engine and run at idling speed.
- Measure fuel pressure.

Specification: Approx. 4.0 bar

If the specification is not obtained:
- Switch ignition off.
- Check whether fuel pump can build up and maintain pressure, Checking non-return valve for fuel pump. [1][2]Fuel Pump, Checking - II
- Check fuel pressure regulator.

If specification is obtained.
- Switch ignition off.
- Check for leaks and holding pressure (compound system). Watch pressure drop on gauge.

After 10 minutes there must be a residual pressure of at least 2.0 bar.

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







- Switch ignition off after pressure has built-up. Simultaneously close pressure gauge V.A.G 1318 cut-off tap (handle cross through-flow direction -arrow-).
- Observe pressure drop (engine side) on gauge.

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

If the pressure does not drop.
- Check non-return valve of fuel pump. [1][2]Fuel Pump, Checking - II
- Check fuel pressure regulator.

Checking fuel pressure regulator

Requirements
- Non-return valve for fuel pump OK.
- Fuel pump supply line OK.

Work sequence
- Remove cover in front of fuse holder.







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







- Connect remote control V.A.G 1348/3A with adapter cable V.A.G 1348/3-2 to contact 28a to fuel pump and battery positive (+).

WARNING: The fuel system is under pressure. Before opening the system place a cloth around the connection. Then release the pressure by carefully loosening the connection.







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

NOTE: To disconnect line slide safety ring -2- into the union -1-.







- Connect pressure gauge V.A.G 1318 with adapter V.A.G 1318/23 and V.A.G 1318/17 to fuel supply line.
- Close pressure gauge shut-off tap (lever diagonal to direction of flow (position -B-).
- Operate remote control V.A.G 1348/3A for approx. 10 seconds to build up a system pressure of approx. 4 bar.
- Observe pressure drop on gauge.

Over a duration of 30 minutes pressure must not drop below 3.2 bar.

If the pressure drops further.
- If the pressure drops further:

If no wiring malfunction is detected:
- Replace fuel pressure regulator.