Fuel Pump (FP), Checking - I
Fuel Pump, Checking
Fuel pump, checking electrically
Fuel pump, checking delivery pressure and delivery rate
Fuel pump, checking electrically
Special tools, testers and auxiliary items required
- Voltage tester V.A.G 1527B
- Multimeter V.A.G 1715 or Vehicle Diagnosis, Testing and Information System VAS 5051
- Wiring diagram
Requirements
- Battery charge at least 11.5V
- Fuses OK
- All electrical consumers, e.g. lights and rear window heating, switched off
Checking function and voltage supply
- Remove cover from fuel delivery unit.
- Switch ignition on. Fuel pump must be heard to run for approx. 2 seconds.
- Switch off ignition.
If the fuel pump does not run:
- Disconnect 4-pin connector from flange on fuel delivery unit.
- Connect diode test lamp V.A.G1527B to outer contacts of connector with auxiliary cables from V.A.G1594 A.
- Switch ignition on.
- LED must light up for approx. 2 seconds.
LED does not light up:
- Check activation of fuel pump relay and check wiring for open and short circuit.
- Vehicle Diagnosis, Testing and Information System VAS 5051 A, Electrical Wiring Diagrams, Troubleshooting Component Locations
LED lights up (voltage supply OK.):
- Remove fuel delivery unit.
- Check that electrical wiring between flange and fuel pump are connected and check for continuity.
If no open circuit can be found:
- Fuel pump faulty, replace fuel delivery unit. Fuel delivery unit, removing and installing.
Checking current draw of fuel pump
- Disconnect 4-pin connector from fuel delivery unit.
- Set multimeter to measuring range 20 A and make a series connection between connector contacts -1 - and fuel pump using adapter cables from V.A.G1594A.
NOTE: Connection can also be made to the current clamp of the multimeter V.A.G1715 or the Vehicle diagnosis, Testing and Information system VAS 5051 to the adapter cables between the contacts -1 - of the connector and the fuel pump.
- Connect contacts - 4 - of connector and fuel pump using adapter cables from V.A.G1594A.
- Start engine and run at idling speed.
- Measure current draw of fuel pump.
- Specification: 3.5 to 4.5Amps
If the measured value is out of specification:
- Replace fuel delivery unit.
Fuel pump, checking delivery pressure and delivery rate
If irregular engine running occurs when driving at high speeds and:
- No faults are stored in the control module Diagnostic Trouble Code (DTC) memory memory, reading and erasing. Manufacturer's Scan Tool
- Tandem pump is OK. Tandem Pump, Checking
- Fuel filter changed at specified intervals, check the delivery pressure and fuel pump delivery rate.
Special tools, testers and auxiliary items required
- Wrench for union nut 3217 or Wrench for union nut T10202 (for metal union nut)
- Pressure tester V.A.G1318
- Adapter V.A.G1318/1
- Adapter V.A.G1318/11
- Adapter set V.A.G1318/17
- Double socket V.A.G1318/23
Special tools, testers and auxiliary items required
- Remote control V.A.G 1348/3A
- Adapter set V.A.G 1594C
Requirements
- Voltage supply OK
- Battery charge at least 12.5 V
- Fuel temperature 15 to 30 degrees C
- Fuel according to DIN EN 590 (no biodiesel)
- Fuel tank filled min.1/4
Work sequence
Observe safety precautions.
Observe rules for cleanliness.
Connect remote control
- Remove cover from fuel delivery unit.
- Disconnect 4-pin connector from fuel delivery unit.
- Connect remote control V.A.G1348/3A to fuel pump contact -1 - and to battery positive (+) using adapter cables from V.A.G1594C.
- Connect contacts - 4 - of connector and fuel pump using adapter cables from V.A.G1594C.
Check delivery pressure and delivery rate
- Pull fuel supply line -1 - off fuel line on suspension turret and connect pressure gauge V.A.G1318 to fuel supply line using adapter V.A.G1318/23 and V.A.G1318/17-8.
- Connect hose V.A.G1318/1 to adapter V.A.G1318/11 of pressure gauge and hold it into a measuring container.
- Close shut-off tap of pressure gauge - position A -.
- Operate remote control V.A.G 1348/3A for approx. 5 seconds.
- Pressure must be 0.5 ± 0.1 bar on pressure gauge
Delivery pressure not achieved:
- Check fuel line to fuel delivery unit.
- If fuel line is OK, replace fuel delivery unit.
When the delivery pressure is achieved, check delivery rate as follows:
- Open shut-off tap on pressure gauge.
- Lever then points in through-flow direction - B -.
- Operate remote control V.A.G1348/3A. At same time slowly close shut-off tap until pressure gauge shows 0.2 bar. Do not continue to operate remote control. From this point on do not move position of shut-off tap.
- Empty measuring container and position under drain hose again.
- Operate remote control for 30 seconds and measure fuel quantity.
- Specification: at least 660 ml/30 s
If the minimum delivery rate is not attained:
- Check fuel line to fuel delivery unit.
- If delivery rate is OK, replace fuel delivery unit.