Volkswagen Workshop Service and Repair Manuals

Special tools, testers and auxiliary items

• ◆ Remote control V.A.G 1348/3A with adapter cable V.A.G 1348/3-2
• ◆ Diode test lamp V.A.G 1527
• ◆ Adapter set V.A.G 1594
• ◆ Ring nut spanner 3217
• ◆ Pressure tester V.A.G 1318
• ◆ Adapter 1318/1
• ◆ Adapter 1318/10
• ◆ Adapter 1318/11
• ◆ Measuring container

Test conditions

• ● Battery voltage OK.
• ● Fuse No. 18 OK.

Test sequence

• ‒ Switch on ignition.

Fuel pump must be heard to run briefly.

If the fuel pump does not run:

• ‒ Switch off ignition.
• ‒ → Pull the fuel pump relay (J17) out of relay plate (relay position 12).

Notes:

• ◆ If tools are necessary to pull relays or control units out of the relay plate, first disconnect battery earth strap.

• ◆ Before disconnecting battery earth strap obtain code for radios with anti-theft coding.

• ‒ → Connect remote control V.A.G 1348/3A with adapter cable V.A.G 1348/3-2 to contact 4 and battery positive (+).
• ‒ Operate remote control.

Fuel pumps run:

• ‒ Check activation of fuel pump relay:

=> Fault finding with V.A.G 1466

Fuel pump does not run:

• ‒ Remove cover in luggage boot floor.
• ‒ Pull connector off fuel tank flange.
• ‒ → Connect diode test lamp V.A.G 1527 with aux. cables from V.A.G 1594 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

LED lights up (voltage supply OK.):

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

If not open circuit can be found:

• ‒ Renew fuel delivery unit.

Checking delivery rate

Test conditions

• ● Voltage supply OK.
• ● Remote control V.A.G 1348/3A connected.

Test sequence

• ‒ Remove filler cap from fuel tank filler neck.

• ‒ Pull the fuel supply pipe off fuel rail.

• ‒ → Connect pressure gauge V.A.G 1318 with adapter 1318/10 to the fuel supply pipe -1- .
• ‒ 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 cut-off tap. The lever then points in the throughflow direction -A-.
• ‒ Operate remote control V.A.G 1348/3A and slowly close cut-off tap, until pressure gauge shows
       1.2 bar.
  From this point on do not move position of cut-off tap.
• ‒ Empty the measuring container.
• ‒ Connect multimeter to vehicle battery to measure voltage using auxiliary cables from V.A.G 1594.
• ‒ Operate remote control for
       30 seconds.

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

     *)     Minimum delivery cm3/30 seconds

     **)     Voltage at fuel pump with engine stationary 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 530 cm3/30 s.

If the minimum delivery rate is not attained:

• ‒ Check the fuel pipes for possible restrictions (kinks) or blockages.
• ‒ → Pull the supply hose -1- off inlet to fuel filter.
• ‒ Connect the pressure gauge V.A.G 1318 to hose with adapter 1318/10.
• ‒ 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:

• ‒ Replace the 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 the multimeter V.A.G 1715 using the current clamp to the red/yellow wire from wiring loom.
• ‒ 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, to do this a 2nd person is necessary.

If the current draw is exceeded:

• ‒ Replace the fuel delivery unit.