Audi Workshop Service and Repair Manuals

Special tools, workshop equipment, test and measuring appliances and auxiliary items required

• ◆ V.A.G 1318 Pressure gauge
• ◆ 1318/9 Adapter
• ◆ V.A.G1318/17 Adapter
• ◆ V.A.G 1348 Fuel quantity comparison meter

Notes:

• ◆ The fuel pressure regulator is located on the fuel filter:

=> Repair group 20; Removing and installing parts of the fuel system; Removing and installing fuel tank with attachments.

• ◆ The specification during this test is dependent upon the working pressure of the fuel pump. This pressure should be approx. 3.0 bar.

Test sequence

• ‒ Remove fuse for fuel pump from fuse holder.

• ‒ → Disconnect the fuel supply pipe coupling -1- (black or black marking) and catch the fuel which escapes with a cloth.

Note:

To do this, press buttons together on hose coupling.

• ‒ → Connect pressure gauge V.A.G 1318 to fuel supply pipe/hose and to hose to fuel rail using adapters 1318/9 and 1318/17.
• ‒ Open the pressure gauge shut-off tap. The lever then points in the direction of flow -A-.
• ‒ Refit fuse for fuel pump in fuse holder.
• ‒ Start the engine and run at idling speed.
• ‒ Measure fuel pressure.
      Specification: Approx. 2.5 bar
• ‒ Switch off ignition.

If the specification is obtained:

• ‒ Check for leaks and holding pressure
  =>Page 24-84.

If the specification is not obtained:

• ‒ Check fuel return pipe between fuel pressure regulator and fuel supply pipe for kinks.

If no kinks are found:

• ‒ Renew fuel pressure regulator.

If the specification is not obtained:

• ‒ Remove fuse for fuel pump from fuse holder.

• ‒ → Reconnect fuel supply pipe -1- and catch fuel which escapes with a cloth.

• ‒ → Pull supply hose -1- off inlet to fuel filter.

Note:

Press buttons on hose couplings to do this.

• ‒ Connect pressure gauge V.A.G 1318 with adapter 1318/17 to fuel supply pipe.
• ‒ Open the pressure gauge shut-off tap. The lever then points in the direction of flow -A-.
• ‒ Refit fuse for fuel pump in fuse holder.
• ‒ Start the engine and run at idling speed.
• ‒ Measure fuel pressure.
      Specification: Approx. 2.5 bar
• ‒ Switch off ignition.

If the specification is not obtained:

• ‒ → Pull fuse No. 28 out of fuse holder.
• ‒ Connect remote control V.A.G 1348/3A with adapter cable V.A.G 1348/3-2 to contact for fuel pump (at the fuse for the fuel pump) and to battery positive (+).
• ‒ Close the pressure gauge shut-off tap.
• ‒ Operate remote control V.A.G 1348/3A and slowly close cut-off tap, until pressure gauge shows
      3 bar.
  From this point on do not move position of cut-off tap.
• ‒ If pressure builds up too high, lower excess pressure by carefully opening the shut-off tap.

If the specification is obtained:

• ‒ Replace fuel pressure regulator.

If the specification is not obtained:

• ‒ Fuel pump defective, renew fuel delivery unit:

=> Repair group 15; Removing and installing fuel delivery unit.

Check for leaks and holding pressure

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

If the pressure does not drop:

• ‒ Check fuel pump non-return valve.

=> Repair group 20; Removing and installing parts of fuel system; checking fuel pump

If the non-return valve is OK:

• ‒ Renew fuel pressure regulator.

Note:

Before removing pressure gauge place a cloth around the connections to be loosened.