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Home >> Volkswagen >> 2004 >> Jetta Sedan (9M2) L4-2.0L (BBW) >> Repair and Diagnosis >> Powertrain Management >> Fuel Delivery and Air Induction >> Fuel Pump >> Testing and Inspection >> Fuel Pump, Check

Fuel Pump, Check



Fuel pump, checking

Engine: BBW

Special tools and equipment








- 3217 Union nut spanner
- VAG 1318 Pressure gauge
- VAG 1318/11 Adapter
- VAG 1318/16 Hose adapter
- VAG 1318/17 Adapter
- VAG 1318/23 Adapter
- VAG 1318/1 Adapter
- VAG 1332 Torque wrench (40 ... 200 Nm)
- VAG 1348/3A Remote control with adapter cable VAG 1348/3-2
- VAG 1466 A Test system
- VAG 1527 B Diode test lamp
- VAG 1594 A Adapter set
- VAG 1715 or Fluke 83 Multimeter
- Measuring container
- Current flow diagram

Requirements





- Fuse No. 28 OK.
- Battery voltage must be at least 11.5 V.
- All electrical consumers, e.g. lights and rear window defroster must be switched off.
- If the vehicle is equipped with air conditioning, this must be switched off.
- On models with an automatic transmission the selector lever must be in position "P" or"N".

Note: Observe description of crash fuel shut-off function.

Checking function and voltage supply

- Remove cover from fuel delivery unit.
- Briefly operate starter.
- Fuel pump must be heard to 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 VAG 1 348/3A with adapter cable VAG 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 wiring diagram:

Fuel pump does not run:






- Take 4-pin connector -1- off flange -3-.






- Connect diode test lamp VAG 1527 B with auxiliary cables from VAG 1594 A to outer contacts of connector.
- Operate remote control.
LED must light up

If LED does not light up:
- Locate and eliminate open circuit using current wiring diagram:

LED lights up (voltage supply OK.):





- Remove flange.
- Check electrical wires between flange and fuel pump for continuity.

If no open circuit can be found:
- Fuel pump is faulty, replace fuel delivery unit.

Checking delivery rate

Requirements

- Voltage supply OK.
- Remote control VAG 1 348/3A connected.

Work sequence
- Remove filler cap from fuel tank filler neck.

WARNING:
- The fuel system is under pressure! Before opening the system place a cloth around the connection. Then release the pressure by carefully loosening the connection.
- Always wear eye protection and wear fuel resistant gloves when disconnecting system connections.






- 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 VAG 1318 with adapter VAG 1318/23 and VAG 1318/17 to fuel supply line.
- Push hose adapter VAG 1318/16 onto adapter VAG 1318/11 on pressure gauge and hold hose in a measuring container.
- Open shut-off tap on pressure gauge. Lever then points in direction of flow -A-.
- Operate remote control VAG 1 348/3A. Then close shut-off tap slowly until pressure gauge shows 3.5 bar pressure. From this point on do not alter setting of shut-off tap.
- Empty measuring container.
- Quantity of fuel delivered by fuel pump depends on battery voltage. Therefore connect multimeter to vehicle battery using adapter cables from VAG 1594 A.
- Operate remote control for 30 seconds and measure battery voltage.






- Compare quantity of fuel delivered with nominal value.
*)Minimum delivery cm3/30 seconds
**)Voltage at fuel pump with engine at rest and pump running (approximately 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 approximately 2 volts less than the battery voltage, the result is a minimum delivery of approximately 500 cm3/30 seconds.

If the minimum delivery rate is not attained:
- Check fuel pressure regulator.

Fuel pressure regulator is OK:
- Check supply line to fuel tank for possible constrictions (kinks).

Supply line is OK:
- Check fuel delivery rate before fuel filter.






- Pull supply line -1- off fuel filter inlet.
- Connect pressure gauge VAG 1318 with adapter VAG 1318/17 as shown.
- Push adapter VAG 1318/1 onto adapter VAG 1318/11 on pressure gauge and hold hose in a measuring container.
- The connector to the suction jet pump must be installed, item-13-.
- Engage fuel delivery unit.
- Connect fuel pump again to current supply.
- Carefully pour in some fuel.
- Cover flange opening (danger of spray).
- Open shut-off tap on pressure gauge. Lever then points in direction of flow -A-.
- Operate remote control VAG 1348/3A. Then close shut-off tap slowly until pressure gauge shows 3.5 bar pressure. From this point on do not alter setting of shut-off tap.
- Empty measuring container.
- Operate remote control again for 30 seconds.






- Compare quantity of fuel delivered with nominal value.
*)Minimum delivery cm3/30 seconds
**)Voltage at fuel pump with engine at rest and pump running (approximately 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 approximately 2 volts less than the battery voltage, the result is a minimum delivery of approximately 415 cm3/30 seconds.

If the minimum delivery rate is now attained:
- Replace fuel filter.

If the minimum delivery rate is again not attained:
- Remove fuel delivery unit and check the strainer filter for soiling.

Only if you have not detected any faults up to now:
- Replace fuel delivery unit.

If the delivery rate has been attained but a fuel supply system fault is still suspected (e.g. intermittent failure of fuel supply system):
- Check current draw of fuel pump as follows:
- Install fuel delivery unit.






- Connect multimeter VAG 1715 to wire (arrow) for contact 1 of 4-pin connector using current pick-up clamp.
- Start engine and run at idling speed.
- Check current draw of 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 the specification:
- Fuel pump is faulty, replace fuel delivery unit.

Check non-return valve for fuel pump

Requirements
- Remote control VAG 1 348/3A connected.






- Pull supply line -1- off fuel filter inlet
- Connect pressure gauge VAG 1318 with adapter VAG 1318/17 as shown.
- Push adapter VAG 1318/1 onto adapter VAG 1318/11 on pressure gauge and hold hose in a measuring container.
- The connector to the suction jet pump must be installed.
- Engage fuel delivery unit.
- Connect fuel pump again to current supply.
- Carefully pour in some fuel.
- Cover flange opening (danger of spray).
- Close pressure gauge shut-off tap (lever diagonal to direction of flow (position -B-).
- Operate remote control at short intervals, until a pressure of approximately 4 bar has built up.

WARNING: Danger of spray when opening the shut-off tap; hold container in front of the free connection on the pressure gauge.

If pressure builds up too high, lower excess pressure by carefully opening shut-off tap.
- Observe pressure drop on gauge.
Over a duration of 30 minutes 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 is faulty, replace fuel delivery unit.
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