Volkswagen Workshop Service and Repair Manuals

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

Special tools, workshop equipment, test and measuring appliances and aux. items required

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

Test conditions

• ● Fuel pump delivery rate OK, checking:

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

Test sequence

• ‒ Pull fuel pump fuse No. 18 out of fuse holder.

• ‒ → Pull off supply pipe/hose -1- from connection at fuel distributor -2- and collect leaking fuel with a cloth.
• ‒ Connect the pressure gauge V.A.G 1318 using adapters V.A.G 1318/10,/11 and /16.
• ‒ Open measured device cut-off tap. (The handle points in through-flow direction -arrow-).
• ‒ Insert fuse 18 (fuel pump) in fuse holder.
• ‒ Start the engine and run at idling speed.

• ‒ Check fuel pressure.
       Specification: Approx. 2.5 bar

If the specification is obtained:

• ‒ → Pull the vacuum hose -1- off connection -2-. The fuel pressure must increase to
       approx. 3.0 bar.
• ‒ 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.
• ‒ → 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 drops again:

• ‒ Check fuel pump non-return valve.

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

If the pressure does not drop:

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

If the pressure does not drop:

• ‒ Renew fuel pressure regulator
  =>Page 24-4 , item 22 .

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, remove fuse 18 again and place a cloth around the connections to be loosened.