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Fuel pump/ECU electrical problem

I have a '72 914 1.7l that sat over the winter and now won't start. It appears as though no power is getting to the fuel pump ever, and I can't figure out why. In searching the forums I found the below test from "Dave at Pelican Parts". #85 on the power supply relay does in fact have 12V while the ignition is on, but #86 on the pump relay always has ground UNLESS the ignition is turned on. I'm leaning toward a bad ECU, but I'm hoping someone might have some more advice for me.

Thanks in advance!



The pump gets its power from the fuel pump relay, which is the relay in front of the rear-most relay on the relay board. The power that gets sent to the pump comes from one of the fuses on the relay board, so verify the fuse. The relay is operated by two things: First, power goes to the "85" pin from the output of the "power supply relay" (the one in front of the fuel pump relay on the board). It has to have +12V, and it should have that at any time the key is in the "on" position. Second, the ECU will supply a ground to pin #86 on the pump relay.

The ECU should ground that pin for about 1.5 seconds when the key goes from "off" to "on", and then again when the starter is cranking, and again when the engine is turning faster than about 50 RPM (as measured by the trigger points in the distributor).

So you can rig a jumper wire from pin 86 to ground, then see if the pump runs when you turn the key on. If it does, then you've checked two of the three conditions that have to be true for the pump to run.

Old 07-18-2013, 02:06 PM
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I would swap relays forst as an initial test, both the mai power and ful pump relays. The ECU's rarely go bad.
Old 07-19-2013, 04:09 PM
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Thanks, I've heard that about the ECU's, but I'm at wits end. I've tried swapping all the relays, to no avail, and they do appear to be clicking when I turn the ignition.
Old 07-21-2013, 09:10 AM
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The next think I would do is go throughthis checklist:

http://members.rennlist.com/pbanders/FPChecklist_frame.htm
Old 07-21-2013, 01:36 PM
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Yeah, thanks. It doesn't seem to work on Safari or Firefox on my Mac, I'll have to try to fire up the old windows box with IE.
Old 07-21-2013, 02:08 PM
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Here are the 8 images in jpg format:






Old 07-22-2013, 07:25 PM
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Thanks for that, I really appreciate it. Now hopefully I can find the time to go through it.

Old 07-22-2013, 07:57 PM
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