Volkswagen Workshop Service and Repair Manuals

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

Special tools, testers and auxiliary items

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

Test conditions

• ● Fuel pump delivery rate OK, checking:

=> Repair group 20, removing and installing parts of the fuel system, checking fuel pump

Test sequence

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

• ‒ → Pull vacuum hose - 1- off connection -2-. The fuel pressure must rise to
       approx. 3.0 bar.
• ‒ Switch off ignition
• ‒ Check for leaks and holding pressure by watching pressure drop on gauge. After 10 minutes there must be
       a residual pressure of
  at least 2 bar.

If the holding pressure drops below 2 bar:

• ‒ Start engine and run at idling speed.
• ‒ → After the pressure has built up switch off ignition and at the same time close pressure tester V.A.G 1318 shut-off tap (handle 90°to throughflow direction -arrow-).
• ‒ Watch pressure drop on gauge.

If the pressure drops again:

• ‒ Check fuel pump non-return valve.

=> Repair group 20, removing and installing parts of the fuel supply system, checking fuel pump

If the pressure does not drop:

• ‒ → Open pressure tester V.A.G 1318 shut-off tap (handle in throughflow direction -arrow-).
• ‒ Start engine and run at idling speed.
• ‒ After the pressure has built up switch off ignition and at the same time clamp-off the return pipe -with blue arrow- on fuel manifold.

If the pressure does not drop:

• ‒ Renew fuel pressure regulator.

If the pressure drops again:

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