Self test then no start

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Jan 4, 2016 | 10:21 PM

dasirish

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Self test then no start

Very new as a member but not to the site and ford trucks. Have an 88 F150 4X4 5.0 with auto trans. Has been running fine(normal) and recently noticed the CEL flickering under hard acceleration. Drove it today back and forth to work, got home shut it down. Went outside to do a self test as described on ford fuel injection.com. Located connectors and followed instructions. This led to key on with a solid CEL(no flashes). I said the heck with it and now it cranks and no start. I don't hear any relays nor the fuel pump with key on. Just looking for a place to start on this. Something simple I'm missing? Fyi...this is my first 80's Ford. Thanks

Jan 4, 2016 | 11:02 PM

88XLTLariat

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From: Plainfield, IN

Test your fuel pump relay. Here's how:Part 1 -How to Test the Ford Fuel Pump Relay (Green Relay)

Jan 4, 2016 | 11:57 PM

dasirish

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88XLTLariat...thanks for the reply will be digging deeper into it tomorrow. Just a little clarification on how I did the test(it seems do differ slightly on a couple different places I searched). Anyway I used a jumper from the self test input(small connector) to battery ground. Also saw the self test with jumper from the STI to the STO...with they both achieve same results or did I screw it up?

Jan 5, 2016 | 12:16 AM

88XLTLariat

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From: Plainfield, IN

Maybe, Subford will chime in, soon. He seems to know alot about the fuel systems.

Jan 5, 2016 | 07:44 AM

subford

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From: Easton,Ks

No relays being picked when the key is turned to run says the ECM Power relay is not being picked. You either have no power to the coil of the power relay (same wire that goes from the Ignition switch to the Ignition Coil) or the relay has lost its ground. Use a loading test light to test for power at the Ignition coil + side.

The STO operates the CEL and you would only connect a meter to this wire in a self test.
Grounding this wire or putting power on it can burn out the STO circuit in the computer and the CEL will no longer work but this should not cause a no start condition.
This has came up before in this 87-96 forum but his engine still ran after he burned out the STO circuit.

Jan 5, 2016 | 08:40 PM

dasirish

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Thanks for all the help and suggestions. I found my problem tonight and hate to say it but way to easy of a fix...but could ahve been a nightmare. In my search for the test connectors I must have bumped some wiring "repairs" by the PO. Of the two relays next to the airbox one was laying on the inner fender, the other (fuel pump relay) still under plastic housing. Appears to me that the PO butt connected the red wire from pump relay(at some point in the loom)back to the (looked like dark blue wire) into the other relay. Hooking the wires back together returned power back to the high current circuit in the fuel pump relay...the low side tested fine in test one. Guess you never know what the heck you may find following anothers work. Thanks again.

Jan 5, 2016 | 09:09 PM

danr1

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From: Sand Lake, MI

Appears to me that the PO butt connected the red wire from pump relay(at some point in the loom)back to the (looked like dark blue wire) into the other relay

That is "factory" and is exactly how you should have found it, the blue section is a fuse link.
Its possible it was replaced, hard to say without seeing it, sounds like if it was they used the proper wire/color/fusing to do it.