Testing Relays and Computer
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From: Southern IN.
Testing Relays and Computer
I put a 5.0 SEFI motor into my 66 F-100 about two years ago with no problems until just recently. The fuel pump stopped pumping. I wired it directly and it works fine. The inertia switch isn't tripped. I replaced the fuel pump relay and still no start. Before I replace the EEC relay is there a way to test it and the computer itself.
I am thinking there was a short,because the day it stopped,I heard a pop under the hood. One of the tad/tab wires came loose and shorted on the fender, possibly frying the computer. I would just like to test it and the EEC relay before I shell out the $.
Thanks, Matt
I am thinking there was a short,because the day it stopped,I heard a pop under the hood. One of the tad/tab wires came loose and shorted on the fender, possibly frying the computer. I would just like to test it and the EEC relay before I shell out the $.
Thanks, Matt
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Senior User
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From: Southern IN.
I checked all the fuses, but not the links. There is power at the fuel pump relay, but it does not seem to be engaging the wire that runs to the fuel pump when the key is switched on. It is a new relay.
Matt
Matt
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From: Louisville,Ky.
The ECM grounds the relay to make it close. Do you have 12V to one large and one small wire going to the relay? If so, try grounding the other small wire and see if the relay clicks and the pump runs.
Lead Driver
Joined: Nov 2002
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From: Concord, NC
Check the fusible link for the computer relay, and the computer relay itself. The TAD and TAB are fed 12V power through the EEC power relay, along with the computer. Like was said above, the computer grounds the FP relay to activate the fuel pumps. Sounds like the computer is not powering up when you turn the key.
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From: Southern IN.
I did trace the fusible link to the EEC and it was toast. Replaced it, but still no start. I am trying to trace all the wires from the relays and check them for continuity. Having a little bit of a hard time tracing them as I buried all the wires in the engine compartment so they wouldn't show. I also can't seem to find my Helms wiring diagragm that shows where they go.
Oh well, tomorrow I will play with it some more.
Thanks, Matt
Oh well, tomorrow I will play with it some more.
Thanks, Matt
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