Fuel Pump, Electrical Testing

WARNING!
Fire hazard. DO NOT smoke or work near heaters of have anything in the area that can ignite fuel.


Special tools and required equipment







- VAG1348/3A with VAG1348/3-2
- VAG1526 A
- VAG1594 A
- VAG1715
Or
- VAS5051 with VAS5051/1

Test requirements
- Battery voltage not less than 12 V







- Fuse S1 OK (in fuse box, blue fuse carrier ST4)







- Fuel pump relay OK (on central electrics in E-box; passengers footwell, relay position 6). Testing:
- Fuel filter OK
- Ignition switched off

Checking voltage supply
- Detach floor covering at front of passenger's footwell.







- Unscrew knurled nut -1-.
- Pull trim -2- out of clip -3- towards the rear.
- Detach trim.







- Disconnect fuse No. S1 out of fuse holder ST4 in fuse box.
ST4 - blue fuse holder







- Connect VAG1348/3A remote control with VAG1348/3-2 adapter cable to lower terminal of socket for fuse No. S1 in fuse holder ST4 -arrow 1-.
- Connect clamp to battery (B+) supply (e.g. socket of 60 Amp fuse -arrow 2- at top of fuse box).
- Press remote control switch.
- Pump should start running audibly.


NOTE: The fuel pump runs very quietly. Where possible, avoid noisy surroundings for this test. If necessary, perform the test with a 2nd mechanic.


If pump does not start running:
- Remove cover for fuel level sender and fuel delivery module under carpet in trunk (right side).







- Release and disconnect 4-pin connector -arrow-.







- Connect multimeter (voltage range) between terminals 1 and 4.
- Press remote control switch.
- Specification: approx. battery voltage

If the specification is not obtained:
- Locate and eliminate open circuit using wiring diagram:

If the specification is obtained, even though the fuel pump did not run:
- Check current draw.
- Remove fuel delivery module.
- Check if wiring between flange and fuel pump is disconnected or broken (test for continuity).

If no wiring malfunction is detected:
- Fuel pump is faulty. Replace fuel delivery module.

Checking current draw

Test requirement:
- Supply voltage for fuel pump OK.







- Connect VAG1348/3A remote control with VAG1348/3-2 adapter cable to lower terminal of socket for fuse No. S1 in fuse holder ST4 -arrow 1-.
- Connect clamp to battery (B+) supply (e.g. socket of 60 A fuse -arrow 2- at top of fuse box).
- Connect vehicle diagnostic, testing and information system VAS5051 or multimeter VAG1715 to remote control cable via current pick-up clamp.
- Press remote control switch.
- Measure current draw of fuel pump.
- Specification: approx. 8 A

If the specification is not obtained:


NOTE: If the indicated current draw is 4 amps, this means the fuel pump is running dry (without fuel).