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 1318/1
• ◆ Adapter 1318/11

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 fuel supply hose (white marking) -1- off connection on fuel rail -2-.
• ‒ Connect pressure gauge V.A.G 1318 using adapter 1318/11 to hose and using adapter 1318/1 to connection on fuel rail.
• ‒ Open measured device cut-off tap. (The handle points in throughflow direction -arrow-).
• ‒ Start engine and run at idling speed.
• ‒ Check fuel pressure.
       Specification: Approx. 2.5 bar

• ‒ → Pull vacuum hose -1- from fuel pressure regulator off -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 engine and run at idling speed.
• ‒ When the pressure has built-up again, switch off ignition and at same time close gauge shut-off tap. The shut-off tap handle is at right-angles to through flow direction.
• ‒ 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 gauge shut-off tap again.
• ‒ Start engine and run at idling speed.

• ‒ → When the pressure has built-up again, switch off ignition and at same time clamp off return supply hose (with blue markings) -1-.

If the pressure does not drop:

• ‒ Renew fuel pressure regulator
  =>Page 24-12 , item 5 .

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 place a cloth around the connections to be loosened.