Audi Workshop Service and Repair Manuals

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

• ◆ 3217 Union nut spanner
• ◆ V.A.G 1318 Pressure tester
• ◆ V.A.G 1318/1 Adapter
• ◆ V.A.G 1318/11 Adapter
• ◆ V.A.G1318/17 Adapter
• ◆ V.A.G 1318/23 Adapter

• ◆ V.A.G 1332 Torque wrench (40...200 Nm)
• ◆ V.A.G 1348 Fuel quantity comparison meter
• ◆ V.A.G 1466 Test system
• ◆ V.A.G 1527 B Diode test lamp
• ◆ V.A.G 1594 A Adapter set
• ◆ V.A.G 1715 Multimeter
• ◆ Measuring container
• ◆ Current flow diagram

Check conditions

• ● → Fuse 28 must be OK.
• ● The battery voltage must be at least 11.5 V.
• ● All electrical consumers, e.g. lights and rear window heating must be switched off.
• ● If the vehicle is equipped with an air conditioning system, this must be switched off.

Note:

Observe functional description of crash fuel shut-off.

Checking function and voltage supply

Note:

Check whether a coded radio is installed as during the forthcoming work sequences the battery earth strap must be disconnected. Obtain radio code first if necessary.

• ‒ Fold rear seat forwards.
• ‒ Remove cover from fuel delivery unit.
• ‒ Switch on ignition. Fuel pump must be heard to run
      briefly -approx. 1 second-.

If the fuel pump does not run:

• ‒ Switch off ignition.
• ‒ Remove cover in front of fuse holder.

• ‒ → 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 28a to fuel pump and battery positive (+).
• ‒ Operate remote control.

Fuel pump runs:

• ‒ Check activation of fuel pump relay using current flow diagram and V.A.G 1466 A:

=> Current flow diagrams, Electrical fault finding and Fitting locations

Fuel pump does not run:

• ‒ Pull 4-pin connector off flange on fuel delivery unit.

• ‒ → Connect diode test lamp V.A.G 1527 B with auxiliary cables from V.A.G 1594 A to the outer contacts of the connector.
• ‒ Operate remote control.
      LED must light up

LED does not light up:

• ‒ Locate and eliminate open circuit using current flow diagram:

=> Current flow diagrams, Electrical fault finding and Fitting locations

LED lights up (voltage supply OK.):

• ‒ → Remove union nut with spanner 3217.
• ‒ Check that the electrical wires between flange and fuel pump are connected.

If no open circuit can be found:

• ‒ Fuel pump defective, renew fuel delivery unit , Removing and installing fuel delivery unit.

Checking delivery rate

Test conditions

• ● The voltage supply for the fuel pump OK.
• ● Remote control V.A.G 1348/3A is still connected.

Test sequence

• ‒ Remove filler cap from fuel tank filler neck.

• ‒ → Pull off supply pipe/hose -1- (with white marking) and collect fuel that leaks out with a cloth.

Note:

Press buttons on hose couplings to do this.

• ‒ → Connect pressure gauge V.A.G 1318 with adapters V.A.G1318/23 and V.A.G 1318/17 to fuel supply pipe.
• ‒ Push the hose V.A.G 1318/1 onto the adapter V.A.G 1318/11 on the pressure gauge and hold hose in a measuring container.
• ‒ Open the pressure gauge shut-off tap. The lever then points in the direction of flow -A-.
• ‒ 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.
• ‒ Empty measuring container.
• ‒ The quantity of fuel delivered by the fuel pump is dependent upon battery voltage. Therefore connect the multimeter with adapter cables from V.A.G 1594 A to the vehicle battery.
• ‒ Operate remote control for
      30 seconds
  and measure battery voltage

• ‒ → Compare the quantity of fuel delivered with specification.

    *)    Minimum delivery cm3/30 seconds

    **)    Voltage at fuel pump with engine stopped and pump running (approx. 2 volts less than battery voltage).

Example:

During the test a voltage of 12.5 volts is measured at the battery. As the voltage at the pump is approx. 2 volts less than the battery voltage then this will equate to a minimum delivery of 200 cm3/30 s.

If the minimum delivery rate is not attained:

• ‒ Check the fuel pipes for possible restrictions (kinks) or blockages.
• ‒ → 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.
• ‒ Repeat delivery rate check.

If the minimum delivery rate is now attained:

• ‒ Replace the fuel filter.

If the minimum delivery rate is again not attained:

• ‒ Remove the fuel delivery unit and check the strainer filter for soiling.

Only when up to now no fault has been detected:

• ‒ Fuel pump defective, renew fuel delivery unit , Removing and installing fuel delivery unit.

If the delivery rate has been attained but nevertheless you suspect a fuel supply system fault (e.g. intermittent failure of fuel supply system):

• ‒ Check the current draw of the fuel pump as follows:

• ‒ Reconnect all disconnected fuel pipes.

• ‒ → Connect multimeter V.A.G 1715 to wire -arrow- for contact 1 of 4-pin connector using the pick-up clamp.
• ‒ Start the engine and run at idling speed.
• ‒ Measure the current draw of the fuel pump.
      Specification: max. 8 amps.

Note:

If the fuel system malfunction is intermittent, you can perform the check during a test drive with the help of a 2nd person.

If the current draw is exceeded:

• ‒ Fuel pump defective, renew fuel delivery unit , Removing and installing fuel delivery unit.

Checking fuel pump non-return valve

Test conditions

• ● Remote control V.A.G 1348/3A is still connected.
• ● Pressure gauge V.A.G 1318 is still connected.

Test sequence

Note:

With this check the fuel supply pipe connections from the fuel delivery unit to the point at which the pressure gauge V.A.G 1318 is connected will be checked for leaks at the same time.

• ‒ → Close pressure gauge shut-off tap (lever at right angles to throughflow direction - position -B-).
• ‒ Separate remote control at short intervals, until a pressure of
      Approx. 3 bar
  has built up.

• ‒ If pressure builds up too high, lower excess pressure by carefully opening the shut-off tap.
• ‒ Watch pressure drop on gauge. After 10 minutes the pressure must not drop below
      2.5 bar.

If the pressure drops further:

• ‒ Check pipe connections for leaks.

If no fault is detected in the wiring:

• ‒ Fuel pump defective, renew fuel delivery unit , Removing and installing fuel delivery unit.