Transfer Pump (Fuel Pump) isn't getting voltage

[thedivision]

Hi all,

I'm dealing with an 87 BMW 325e. This model has two fuel pumps - one inside the tank (transfer pump) and one external (main pump). I thought my transfer pump was bad. Turns out, it's the wiring.

I bridged the fuel pump relay and tested for voltage, got 0.02V. I've been looking for wiring diagrams all day, no luck.

Any idea on how to start diagnosing this issue?

Thanks

[German Audio Specialties]

First off, lets get you that diagram. Go to www.wedophones.com and look at the link for MANUALS, you will find it under the automotive section. What you will find is the correct factory electrical troubleshooting manual, AKA the ETM.

Second, AFAIK, both pumps use the same wire and are not independently controlled.

GL and HTH,
Luke

[jlevie]

The wire from the fuel pump fuse runs along the left side of the interior. There is a splice in the wire around where the rear fender is with one wire running to the transfer pump and another running to the high pressure pump. If you have power to the high pressure pump, but not to the transfer pump, the fault will probably be in the wiring above the gas tank.

[thedivision]

Bingo. Just finished fixing it. The fuel pump 12v wire splits off somewhere in the rear as jlevie said, then travels under the rear seat to the passenger side. There is a little section of wire that travels through a grommet under the passenger side rear seat to the pump (top of the tank), about 10"-15". Since it's now outside the car, it's exposed to the elements. It was corroded just passed the grommet (going outside). I spliced in a new wire and wired it up inside the car. The pump was fine. The car drives a thousand times better now. I think this solved my hesitation problem as well.

Thanks