Volkswagen Workshop Service and Repair Manuals

The fuel pressure regulator controls the fuel pressure dependent upon intake manifold pressure.

The specifications are dependent upon the fuel pump working pressure. This is
     approx. 4 bar

Special tools, testers and auxiliary items

• ◆ Pressure tester V.A.G 1318
• ◆ Adapter 1318/10
• ◆ Adapter 1318/11
• ◆ Adapter 1318/16

Test sequence

• ‒ → Pull fuel supply pipe -1- off fuel manifold connection -2- and connect to pressure gauge V.A.G 1318 using adapter 1318/10.
• ‒ Connect pressure gauge V.A.G 1318 to fuel manifold -2- using adapter 1318/11 and 1318/16. Open pressure gauge cut-off tap (handle in throughflow direction -arrow-).
• ‒ Start the engine and run at idling speed.
• ‒ Check fuel pressure.
       Specification: Approx. 2.5 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 attained:

Engine codes ADY, AGG, AKR

• ‒ → Pull vacuum hose - 1- off connection -2-. The fuel pressure must rise to
       approx. 3.0 bar.

Engine codes AFT, AKS

• ‒ → Pull vacuum hose - 1- off connection -2-. The fuel pressure must rise to
       approx. 3.0 bar.

Continued for all engine codes

• ‒ 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.

When the fuel pump has built-up the pressure again:

• ‒ Switch off ignition and use a second mechanic to seal the return pipe -with blue marking- on fuel manifold with a clamp.
• ‒ Watch pressure drop on gauge.

If the pressure does not drop:

• ‒ Renew fuel pressure regulator , item 19 .

If the pressure drops again:

• ‒ Check pressure gauge for leaks.
• ‒ Check pipe connections, O rings on fuel manifold and injectors for leaks.
• ‒ Check fuel pump non-return valve:

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

When the pressure gauge is removed after completing the test:

• ‒ Switch off ignition.

• ‒ Hold a measuring container before the pressure gauge cut-off tap.
• ‒ → Open pressure gauge cut-off tap -arrow- carefully and release pressure.