Volkswagen Workshop Service and Repair Manuals

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

Special tools, workshop equipment, test and measuring appliances and aux. items required

• ◆ V.A.G 1318 Pressure gauge
• ◆ 1318/9 Adapter
• ◆ 1318/17 Adapter

Test sequence

• ‒ Pull fuel pump fuse No. 28 out of fuse holder.

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

• ‒ → Connect pressure gauge V.A.G 1318 to fuel supply pipe and to fuel rail using adapters 1318/9 and 1318/17.
• ‒ Open shut-off tap on pressure gauge. The handle points in direction of flow.
• ‒ Insert fuel pump fuse No. 28 into fuse holder.
• ‒ Start the engine and run at idling speed.
• ‒ Measure fuel pressure.
       Specification: Approx. 2.5 bar

• ‒ → Pull the vacuum hose off fuel pressure regulator -arrow- . The fuel pressure must increase to
       approx. 3.0 bar.

If the specification is not obtained:

• ‒ Check quantity supplied by fuel pump.

=> Rep. Gr. 20; Removing and installing parts of fuel system; checking 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 the engine and run at idling 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.

=> Rep. Gr. 20; Removing and installing parts of fuel system; checking fuel pump

If the pressure drops again:

• ‒ → Open pressure tester V.A.G 1318 shut-off tap (handle in through-flow direction).
• ‒ Start the engine and run at idling 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:

• ‒ Renew fuel pressure regulator

If the pressure drops again:

• ‒ Check pipe connections, O rings on fuel rail and injectors for leaks.
• ‒ Check pressure gauge for leaks.

Note:

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