Volkswagen Workshop Service and Repair Manuals

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

Special tools, testers, measuring instruments and auxiliary items required

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

Test conditions

• ● Fuel pump delivery rate OK, checking delivery rate:

=> Repair group 20; Removing and installing parts of the fuel supply system; Checking fuel pump

Test sequence

• ‒ → Pull the fuel supply hose (white marking) -1- off fuel supple pipe -2-.
• ‒ Connect pressure measured device V.A.G 1318 using adapter 1318/10 to hose and using adapters /11 and /16 to fuel supply pipe.
• ‒ Open measured device cut-off tap. (The handle points in throughflow direction -arrow-).
• ‒ Start the engine and run at idling speed.
• ‒ Measure fuel pressure.
       Specification: Approx. 2.5 bar

• ‒ → Pull vacuum hose off fuel pressure regulator -1- at intake pipe -2-. The fuel pressure must
       increase
  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 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 throughflow direction -arrow-).
• ‒ Observe pressure drop on gauge.

If the pressure does not drop:

• ‒ Check fuel pump non-return valve.

=> Repair group 20; Removing and installing parts of the fuel supply system; Checking fuel pump non-return valve.

If the pressure drops again:

• ‒ → Open pressure tester V.A.G 1318 shut-off tap (handle in throughflow direction -arrow-).
• ‒ Start the engine and run at idling speed.
• ‒ Switch ignition off after the pressure has build-up. At the same time pinch/seal the return hose (with blue marking) -3- together.

If the pressure does not drop:

• ‒ Renew fuel pressure regulator
  =>Page 24-12 , item 4 .

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.