Wiring harness replacement 1985 302 efi

Where can I find a wiring harness replacement for a 85 302 efi. New or used (in great shape) Would one for an 86 be the same. At this point im seriously considering swapping to a carb. I have about 8 grand into this motor at this point. This wiring gremlin kicked my .....

There are several different harnii for each truck.  There's one that runs from the left headlight, across the dash, and out to the right headlight.  And there's one that plugs into that one for the ignition and sending units on the engine.  And there's one that runs to the rear.  Plus add-on ones for things like speed control, backup lights, etc. So you won't find "a" harness for your truck.

As for the difference between '85 and '86, there were some significant differences in the fuel pump wiring in that timeframe.  But some 85's were wired one way and some 85's another.

What part(s) of yours are bad?

Update 6342...I had a spare eec plugged it in and gremlin is gone again. Something is shorting out the eec(2 now) I ordered a used wiring harness with matching eec.
My number 2 injector keeps causing a vapor lock. That might be the short.

Something I would do with your existing harness, or the new one, is to re-wrap it or wrap over the original wrap, and make sure it's nice and tight. Add clamps or whatever you can where the harness can move or wiggle as the truck goes over bumps, etc. I'm a bit OCD when it comes to wiring both new and old in that it must be secured everywhere, and covered, and not able to budge or move (unless of course it's supposed to, like between the engine and the cab or the engine and the fender, etc).

I used to spend a lot of time working on industrial equipment chasing wiring faults, and when I found them it was almost always due to chafing where the wires could move from vibrations or whatever. They would also crack and break inside connectors a lot too.

They're a pain to find.

PS: I watched an old guy years ago...crude as it may be, he kept installing larger and larger fuses in a machine's panel until a circuit board went up in smoke. He pointed and said "there's the problem, right there!" haha. True story. We installed a new circuit board and the machine worked fine afterwards lol.

Back in high school my auto shop teacher would call that “smoking it out” . Along with “ that aint how we do it”  but i guess as long as there are no gas leaks one might get by with it.
Not on my truck!

I'm running this MF Gremlin down. I've not worked this hard since chasing down some HVTs in Samarra Iraq....
Is there any "possible" way a short in the injectors harness could short out the eec?

Waine5550, I have a lot of experience chasing gremlins in my 1986 Bronco with the 5.0 and EFI. After fixing so many issues with shorts and ignition, I ended up finding a NOS harness for an 88 and remaking it into the perfect harness for an 86. I replaced every sensor, every single wire, every unit,

Basically, the answer to your question is that it's not too likely for a short in the harness to mess up the ECU internally. There are a couple of circuits in the TFI part of the harness that require a resistor. I guess if the resistor failed and the full voltage was passed through it instead, it could cause damage. Are you sure it's something in the injector segment?

No not sure. I just know the number 2 cylinder keeps vapor locking. I have had 3 different injector in there all tested fine. Had three different eecs they keep going out. Relay connectors had been three times and 3 new relays. Im Changing the wire harness out next. Didn't know if I had/should take the upper intake off and change out the injector harness.

One other question. The fuse for the aux fuel; I pulled it and the pump still would run. Is this fuse for the tank low pressure pump?

aux fuel? that sounds like an add on tank. twin tanks just had a selector switch on the heat / ac control panel on the right hand side which said front/ rear. not aux fuel.

Back in the 80's I worked at a Chevy dealer and on those a shorted solenoid or injector could take out an ECM, I don't know if this is the same with an 80's Ford or not. I would seriously consider removing and inspecting the injector harness.

Fuse 15 is for trucks with 2 tanks.....



EXCEPT It's not used in the 5.0 EFI. (as shown in the '85 EVTM)






These use fuse link (N)  as part of wire 301.

Some time in the past 37 years somebody probably just put a fuse in there because it made them feel better.