no electric to fuel pump

Wed Apr 08, 2009 9:21 pm

hi people here's the problem i no the fuel pump works but there is no electric going to it?
i have a 318is e30 is there a cut off switch or fuse or relay that im missing as i cant find one it works if i go direct to the battery but alot of hassel having to connect and undo everytime i need to start
should i save the grief and go negitive to the battery and positive to the ignition JOB DONE?

any help will be great

Wed Apr 08, 2009 9:37 pm

I am sure there is a relay that is triggered either by another relay or the ECU. I know what they are on a 325 but not 318. The pump needs to be off when the engine stops for safety reasons.

Wed Apr 08, 2009 9:55 pm

i no the ecu is working good im 85% sure its the relay thats why i was thinking running new wires to the ignition that way it will turn on and of through the key not manual

Wed Apr 08, 2009 10:23 pm

Fuse 11 is the fuel pump fuse, and should be 7.5A. If it has blown, and a new fuse appears to cure the problem, you probably have the first signs of a failing fuel pump.
The fuel pump relay can go faulty, and on a four pot, is found under the bulkhead wiring cover.
It is usually orange in colour (can be blue), and can be exchanged , for testing purposes, with any of the orange relays in the fusebox.
Does this car produce sparks when cranked?
No rewiring is required or desirable. Your car has a fault - find it!

Wed Apr 08, 2009 11:27 pm

yeah spark is good tested that must be the relay done all electric tests pump is ok hopefully i get the right fuse how many relays are under there do you no hopefully not to many lol

Wed Apr 08, 2009 11:45 pm

There are normally two relays under the cover, plus an empty socket. The extra socket is for a relay for the heater of an oxygen (lambda) sensor, and is only fitted to cars with cats, etc.
The white relay is the DME relay, and power to the coil of the fuel pump relay is switched by this, so it can give similar symptoms.
Pull the fuel pump relay out, and use a short piece of wire to link together pins 30 and 87 of its socket. This should make the pump run continuously.