Volkswagen Workshop Service and Repair Manuals

Special tools, workshop equipment, testers, measuring instruments and auxiliary items required

• ◆ 3217 Union nut spanner
• ◆ V.A.G 1318 Pressure gauge
• ◆ V.A.G 1318/11 Adapter
• ◆ V.A.G 1318/16 Hose adapter
• ◆ V.A.G 1318/17 Adapter
• ◆ V.A.G 1318/23 Adapter
• ◆ V.A.G 1318/1 Adapter

• ◆ V.A.G 1332 Torque wrench (40 ... 200 Nm)
• ◆ V.A.G 1348/3A Remote control with adapter cable V.A.G 1348/3-2
• ◆ V.A.G 1466 A 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

Test prerequisites

• ● → Fuse No. 28 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 air conditioning, this must be switched off.
• ● On models with an automatic gearbox selector lever in position "P" or "N"

Note:

Observe description of function of crash fuel shut-off.

Checking function and voltage supply

• ‒ Remove cover from fuel delivery unit.
• ‒ Briefly operate starter. Fuel pump must be
      audibly
  run.
• ‒ Switch off ignition.

If the fuel pump does not run:

• ‒ 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 referring to current flow diagram:

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

Fuel pump does not run:

• ‒ → Pull 4-pin connector -1- off flange -3-.

• ‒ → Connect diode test lamp V.A.G 1527 B with aux. 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 flange.
• ‒ Check the electrical wires between flange and fuel pump for continuity.

If no open circuit can be found:

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

Checking delivery rate

Test prerequisites

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

Test sequence

• ‒ Remove filler cap from fuel tank filler neck.

• ‒ → Pull off supply line -1- and collect leaking fuel with a cloth.

Note:

To do this slide safety ring -2- into the union -1-.

• ‒ → Connect pressure gauge V.A.G 1318 with adapter V.A.G 1318/23 and V.A.G 1318/17 to the fuel supply pipe.
• ‒ Push hose adapter V.A.G 1318/16 ono adapter V.A.G 1318/11 on pressure gauge and hold hose in a measuring container.
• ‒ Open shut-off tap on pressure gauge. The lever then points in direction of flow -A-.
• ‒ Operate the remote control V.A.G 1348/3A. Then close the shut-off tap slowly, until the pressure gauge shows
      3,5 bar pressure. From now on do not alter the setting of the shut-off tap.
• ‒ Empty measuring container.
• ‒ The quantity of fuel delivered by the fuel pump depends on the battery voltage. Therefore conect multimeter to vehicle battery using adapter cables from V.A.G 1594 A.
• ‒ Operate remote control for
      30 seconds
  and measure battery voltage.

• ‒ → Compare the quantity of fuel delivered with nominal value.

    *)    Minimum delivery cm3/30 seconds

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

Example:

During the test, a voltage of 12,0 volts is measured at the battery. As the voltage at the pump is approx. 2 volts less than the battery voltage, the result is a minimum delivery of approx. 500 cm3/30 seconds.

If the minimum delivery rate is not attained:

• ‒ Check fuel pressure regulator => Page 24-38.

If the fuel pressure regulator is OK.:

• ‒ Check supply pipe to the fuel tank for possible constrictions (kinks).

If the supply pipe is OK.:

• ‒ Check fuel delivery rate before the fuel filter.

• ‒ → Pull supply pipe -1- off fuel filter inlet => Page20-14, Removing and installing fuel delivery unity unit.
• ‒ Connect pressure gauge V.A.G 1318 with adapter V.A.G 1318/17 as shown.
• ‒ Push the adapter V.A.G 1318/1 onto the adapter V.A.G 1318/11 on the pressure gauge and hold hose in a measuring container.
• ‒ The connector to the suction jet pump must be fitted => Page 20-5, item 13.
• ‒ Engage the fuel delivery unit.
• ‒ Connect the fuel pump again to the current supply.
• ‒ Fill some fuel in again.
• ‒ Cover the flange opening (danger of spray).
• ‒ Open shut-off tap on pressure gauge. The lever then points in direction of flow -A-.

• ‒ Operate the remote control V.A.G 1348/3A. Then close the shut-off tap slowly, until the pressure gauge shows
      3,5 bar pressure. From now on do not alter the setting of the shut-off tap.
• ‒ Empty measuring container.
• ‒ Operate remote control again for
      30 seconds.

• ‒ → Compare the quantity of fuel delivered with nominal value.

    *)    Minimum delivery cm3/30 seconds

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

Note:

Due to the operating of the suction jet pump the minimum delivery rate before the fuel filter/pressure regulator is lower.

Example:

During the test, a voltage of 12,0 volts is measured at the battery. As the voltage at the pump is approx. 2 volts less than the battery voltage, the result is a minimum delivery of approx. 415 cm3/30 seconds.

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 if you have not detected any faults up to now:

• ‒ Replace the fuel delivery unit.

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

• ‒ Check the current draw of the fuel pump as follows:
• ‒ Install fuel delivery unit=> page 20-18.

• ‒ → Connect multimeter V.A.G 1715 to wire -arrow- for contact 1 of 4-pin connector using current pick-up clamp.
• ‒ Start engine and run at idling speed.
• ‒ Check the current draw of the fuel pump.
      Specification: max. 9 amps.

Note:

If the fuel system malfunction is intermittent, a check during a road test can be performed with the help of a 2nd person.

If the current draw exceeds:

• ‒ Fuel pump defective, renew fuel delivery unit=> Page 20-14.

Check non-return valve for fuel pump

Test prerequisites

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

• ‒ → Pull supply pipe -1- off fuel filter inlet => Page20-14, Removing and installing fuel delivery unity unit.
• ‒ Connect pressure gauge V.A.G 1318 with adapter V.A.G 1318/17 as shown.
• ‒ Push the adapter V.A.G 1318/1 onto the adapter V.A.G 1318/11 on the pressure gauge and hold hose in a measuring container.
• ‒ The connector to the suction jet pump must be fitted => Page 20-5, item 13.
• ‒ Engage the fuel delivery unit.
• ‒ Connect the fuel pump again to the current supply.
• ‒ Fill some fuel in again.
• ‒ Cover the flange opening (danger of spray).
• ‒ Close pressure gauge shut-off tap (lever diagonally to direction of flow -position -B-).

• ‒ Operate remote control at short intervals, until a pressure of
      approx. 4 bar
  has built up.

• ‒ If pressure builds up too high, lower excess pressure by carefully opening the shut-off tap.
• ‒ Observe pressure drop on gauge. Over a duration of 30 minutes the pressure must not drop below
      3,2 bar.

If the pressure drops further:

• ‒ Check line connections for leaks.

If no wiring fault is detected:

• ‒ Fuel pump defective, renew fuel delivery unit=> Page 20-14.