Engine harness differences

Topic: Engine harness differences (Read 2474 times) previous topic - next topic

Engine harness differences

October 31, 2005, 02:36:31 AM

I have an '86 cougar with a motor out of an '86 bird. My problem is that when the guy that did my motor swap did it, he cut the original harness all to $h!t and his replacement was a harness from an '87 cougar. My question is, could the difference in years on the harness be the reason that my car wont run?

Engine harness differences

Reply #1 – October 31, 2005, 09:56:49 PM

Somebody has to know something about this one.
Engine/Computer 86 SO
Harness 87

I don't think they are directly compatible but don't know the specifics.

Engine harness differences

Reply #2 – November 01, 2005, 10:47:56 AM

The '87 and '88 harnesses have some differences, not sure about the '86...

Problem with your question is there can be 10-20 different things that are causing your no start problem... Does it have spark??? Is the fuel pump running when you first turn on the ign sw??? If not, is there power to the pump?? Is the EEC powering up?? If you can't do some basic troubleshooting, this is gonna be a hopeless case...

Engine harness differences

Reply #3 – November 01, 2005, 06:10:27 PM

Quote from: TurboCoupe50

The '87 and '88 harnesses have some differences, not sure about the '86...

Problem with your question is there can be 10-20 different things that are causing your no start problem... Does it have spark??? Is the fuel pump running when you first turn on the ign sw??? If not, is there power to the pump?? Is the EEC powering up?? If you can't do some basic troubleshooting, this is gonna be a hopeless case...

That's what is causing all my confusion, I've replaced the plugs, wires, cap and rotor, fuel pump, fuel pump relay, reset the inertia switch, almost everything I can think of. It gets spark, and everything turns on and runs like it should, I'm just not getting fuel into the injectors. I know the motor runs good, because before we pulled it out of the bird, I fired it up and took it down the road. It's just that when the swap was going on, the guy I had working on it cut the original harness right after the firewall. His replacement harness was an '87's and even that is chopped up a little bit (by him, again) and I don't really know what to do anymore.

Engine harness differences

Reply #4 – November 02, 2005, 04:36:49 AM

OK I take it you have fuel pressure at the rail??? Even then you should be reading codes and stop chasing snakes through the woods. If there's F/P, these are the most probable causes.

1... Problem in the TPS circuit shutting down the injectors, this WILL throw a code(Bad TPS or wiring harness).

2... No voltage to the injectors(wiring harness).

3... No ignition pulse to the EEC, so it doesn' know to fire the injectors(wiring harness).

4... Clogged/bad injectors(doubtful).

OK take it and run...

Engine harness differences

Reply #5 – November 02, 2005, 05:55:44 PM

Thanks guys for the help, I guess now I have to find someone with a diagnostic tester and see what shows up. Yea, I'm getting pressure at the rails, I pulled the gas line off at the rail and I definitely got pressure. I'm kinda leaning towards the harness being bad though, only for the fact that I know the motor ran before it was pulled, but who knows, a year of sitting may have done some damage, never hurts to give it a try, right?

Engine harness differences

Reply #6 – November 06, 2005, 01:56:53 PM

was your car a origanlly a v-6 car? if it was then you have the wrong pump the sefi uses a higher pressure pump than the tbi.

Engine harness differences

Reply #7 – January 06, 2012, 07:23:47 PM

I have an 84 T-bird with the 5.0 liter. I am having intermitent problems with it cranking. While replacing the hoses I found that it I moved the cam sensor wire (close to where they connect to the distributor) the car would stop running and then may or may not crank. If I wiggle the wires and got it to crank, it will run as long as I don't move the wires. Just something you could check.

I replaced about a foot of the cam sensor wires and the plug into the distributor and it still does it. Does anybody on here know where you can buy a new engine harness for an 84 with a 5.0. I figure if my cam sensor wires are going bad, I might as well change out the whole harness, but cant find out where to get a harness other than generic harnesses that would take a lot of time to modify in order to make them fit.

Engine harness differences

Reply #8 – January 07, 2012, 02:21:18 AM

Junkyard? No idea where your at, so I can't recommend much. More likely then not its a bad ground or single wire. Post up a new thread, either a trouble shooting thread, or wanted thread. You may need more posts to post in classifieds.

Engine harness differences

Reply #9 – January 07, 2012, 03:39:56 AM

WTF is a cam sensor wire?

Engine harness differences

Reply #10 – January 07, 2012, 04:48:41 AM

There was a knock sensor in some of the earlier birds. That is what I took it as.

Engine harness differences

Reply #11 – January 07, 2012, 11:12:05 AM

Quote from: ThunderbirdSport302;377169

WTF is a cam sensor wire?

PIP or TFI wiring?

Engine harness differences

Reply #12 – January 07, 2012, 12:01:15 PM

Thanks Haystack.
Thunderbird Sport302. It is the 2 or 3 wire bundle that ties into the distributor. It usually has an aluminun sheilding around it. Mine has aluminum braid surrounding the wires. On new harnesses, it can look like a foil wrap around the wires.