Volkswagen Workshop Service and Repair Manuals

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

The specification for the check is dependent upon the working pressure of the fuel pump. This is

     approx. 3.0 bar

Special tools, workshop equipment, test and measuring appliances and auxiliary items required

• ◆ V.A.G 1318 Pressure gauge
• ◆ V.A.G 1318/10 Adapter
• ◆ V.A.G 1318/11 Adapter
• ◆ V.A.G 1318/16 Hose adapter
• ◆ V.A.G 1921 Spring-type clip pliers

Test sequence

• ‒ Pull fuel pump fuse No. 40 out of fuse holder.
• ‒ Remove air cleaner , Fig. 3 .
• ‒ → Pull off supply pipe/hose -1- (with white marking) and collect fuel that leaks out with a cloth.

• ‒ → Connect pressure gauge V.A.G 1318 with adapter V.A.G 1318/10 to supply hose -1- and with adapter V.A.G 1318/11 and hose adapter V.A.G 1318/16 to supply pipe.
• ‒ Open shut-off tap on pressure gauge. The handle points in direction of flow.

• ‒ Insert fuel pump fuse No. 40 into fuse holder.
• ‒ Start the engine and run at idling speed.
• ‒ Measure fuel pressure.
       Specification: Approx. 2.5 bar

• ‒ → 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.

=> Rep. Gr. 20; Removing and installing parts of fuel system; checking 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 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 gauge V.A.G 1318 shut-off tap (handle in direction of flow).
• ‒ Start the engine and run at idling speed.

• ‒ → Switch ignition off after the pressure has build-up. At the same time clamp-off the return hose (with blue marking) -2-.

If the pressure does not drop:

• ‒ Renew fuel pressure regulator
  , item 5 .

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.