Okay, I got an engine bay wiring harness from an identical truck, but after hooking it all up the fuel pump does not prime when I turn the key. Everything else works as far as I can tell, including cranking the engine, blinkers, etc, but there is no fuel pump prime when the key is turned.

 

Identical as in same year? If not, then the wiring pinouts are probably different which is why the fuel pump isn’t priming.

 

I figured it out. Yes, same year. The problem was I hadn't connected the inertial switch on the passenger kick panel. Now the fuel pump primes, engine cranks, but engine does not start. Possibly a ground wire or other connector in the dash that just isn't hooked up yet. We will see.

 

You're getting close. Are you getting spark at the plugs?
If you have fuel, spark and air but the motor doesn't run the timing may just be off a little, has the distributor been moved?

 

I'm not sure about spark at the plugs, but I doubt it's related to engine timing. The engine ran great up until I removed it from my one truck and then put it in this one. It's definitely a wiring issue, but I'm not sure where yet. The dashboard isn't in all the way, so I will finish hooking it all up before assuming it's a problem with the harness.

 

Okay, I was not expecting this, but when I pulled the plug from cylinder one and had my wife crank the engine, it did indeed have spark.

When I crank the engine nothing happens aside from that. There is no sputtering or attempting to start or combustion of any kind. Therefore, since I am getting spark and presumably air, it must be the case that I am not getting fuel, correct? The fuel pump primes when I turn the key, so it seems the culprit is that the injectors are not firing?

 

I could really use some help with this from someone... I hate to be a bother, but this is really holding up a lot of important stuff. I don't know what the problem is, and I don't even know what to check next or where to go from here. I might just part this stupid truck out.

 

That would seem to be the case.

Is the harness you have now all from one truck? If not what years and models are the sections from?
Do you have a 300 I6 PCM in it now?

 

Was able to pull codes.

114
116
552 - this one is new.
558 - this one is new.
636
654

Current theory: Engine harness is 1994, engine bay harness is 1996. Did the pinout of either side of c101 change in that time?

 

114 - IAT out of range
116 - ECT out of range
552 - AIRB circuit fault
558 - EVR fault
636 - TOT out of range
654 - Trans selector not in park

Last one could be a problem, the temp sensors can be ignored because the engine/trans is cold and the other smog system codes won't prevent it from starting.

Ford is notorious for changing connector pinouts. The '96 harness is from a F250 isn't it? I just want to make sure neither of the donors were MAF.
What I'd suggest is taking apart the connector at C101 and check that there are the same number of wires on each side and that they are in the same pin positions. Wire colors won't match so don't worry about that.

 

Neither of the trucks were MAF.

Well, I didn't have to count the number of pins. Many of them are not in the same place at all, which likely means the ones that are there aren't the same either. I can't find a pinout diagram for that year at all, and I have no interest at all in buying an EVTM for two years of trucks. 4.9L 1996 F-250s with GVWR 8501+ are as rare as can be, so I have very little chance of finding a compatible wiring harness, either.

 

If you still have the engine wiring for the V8, could you ohm out the wires going to each sensor/injector to see which pin the go back to on the connector... then move the I6 wire to the corresponding pin found on the V8 wiring?

 

We need somebody with an EVTM for either a '94 or '96 SD truck to post up a pinout for C101, that would make this a lot quicker.
But you will still have to get the multimeter out and trace some wires for the other side.

You can do this from scratch of course, get a pen and paper, multimeter or test light will work too.
Disconnect the battery.
Disconnect the PCM.
Break apart C101 and make a list of the pin locations that have wires, and then find what pins they go to at the PCM connector. The PCM pinout is all standard and never changed so then you know what signals are where so it's just a matter of matching up the other side, and these connectors come apart so the wires can be moved without doing any cutting or splicing.
Chances are most of the wires are in the correct locations and you only have to move a few, that means you're actually a lot closer than you might think.

 

That's a good idea, and not that complicated overall. In the absence of EVTMs it could still work.

 

1994 F Series C101 Diagram Gas Engine




1996 F Series C101 Diagram Gas Engine