fuel pump problems

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ChrisR
E30 Zone Newbie
E30 Zone Newbie
Posts: 12
Joined: Mon May 23, 2005 11:00 pm

Tue Jan 01, 2008 9:02 pm

I'm stuck!

I've just swapped the engine on my track car - cracked head on the original.

The new engine ran fine in the donor car and the original engine ran but the new engine won't run in the car, the only problem I can find is the fuel pump isn't priming.

I've tried the following but have the same problem:

1. swapped engine loom for orginal

2. swapped the relays and 'shorted' the 30-87 relay terminals

3. the pump runs out of the tank and runs fine in the tank when I short it across the fuse box (this is the only way I can get fuel at the rail)

4. all the engine accessories were good when the engine last ran

5.everything is connected

Any ideas I'm at a total loss?

Chris
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Brianmoooore
E30 Zone Team Member
E30 Zone Team Member
Posts: 49353
Joined: Mon Jan 10, 2005 11:00 pm

Wed Jan 02, 2008 12:54 am

Very few E30s prime the fuel system when the ignition is turned on!
On most, the fuel pump runs only when the crankshaft is turning.
You say you've hot wired the fuel pump, and it runs, but presumably the engine still doesn't run? If so, you probably don't have sparks at the plugs either.
The usual reasons for this are: a) either the ECU isn't getting its permanent live from the battery, its ignition switched lives from the main ECU (DME) relay, or its feed from the ignition switch, or b) the crank position sensor is faulty or not connected.
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