intermittent fault now permanent no power to fuel pump.

[spbt1]

Hi guys, my intermittent fault that has rendered my car unusable for the last 3 years has now become permanent.

86 325i sport tech 1 with motronic 1.1

Basically i have lost power to the fuel pump, i have carried out the checks as per the wiki, The fuel pimp works when on the bench, the relay works and the DME is also fine, i have checked the fuel pump fuse number 11,

When bridging pins 30 and 87 i stil get no power at the pump.

So the Question is, What to do next and is there a usual point of failure in the wiring that feeds to the pump or is there something else that i can do. The car has been changed onto the later motronic in an attempt to resolve my break downs but it is no a permanent failing


any advice would be greatly appreciated.

[spbt1]

thanks for that will, i have live at pin30

[Brianmoooore]

i have live at pin30

Must be checked with something like a bulb - a positive result with a meter will be meaningless.
No common places for the wiring to fail, but quite common to find an immobiliser connected into the line.

[spbt1]

My car does have an aftermarket alarm the make of I'm unsure, it has a two pin half circle type affair that you have to connect to plug on the dash which then allows ignition lights could this also be connected to the fuel power supply.

If so is it a big job to remove it altogether.

Thanks gents

[spbt1]

if i carefully remove the alarm and imobiliser and all of its subsequent wire do we think that will resolve it,

[Brianmoooore]

if i carefully remove the alarm and imobiliser and all of its subsequent wire do we think that will resolve it,

To state the obvious, it will if it's the problem.
First thing to do is to check if it's connected to the fuel pump wiring. You are looking for a green/purple wire which runs from the pump relay to through pin 13 of the 20 pin C101 engine loom to body plug, where it becomes purple/red for the short journey to fuse 11 in the fusebox.
From here, it reverts to green/purple, goes down through the duct under the fusebox and appears in the cabin behind the glovebox area. It then goes across to the left, down behind the front speaker panel, and back along the LH sill, until it reaches the rear seat pan.
Goes across the seat pan to a 8 pin plug and socket cable tied to the vent pipe tube on the RH side, disappears down through a grommet in the seat pan, and back over the rear of the tank to the pump.

[spbt1]

Thanks for the info brian (priceless) i now know where to look first thing is to remove the alarm.

Thanks again.

[spbt1]

Problem solved, Brian you were right, the green/purple wire had been cut under the fuse box and wired into the immobiliser, rewired back to normal and hey presto, she's alive again.


Thanks chaps