92 4.0 swap wont run

[RobbieD]

On the drivers side of the engine harness, there is a male grey 8 pin plug with that red/green wire. Should that be spliced into the column wiring?

Does it look like this:

If so that's C102 and you can get ignition power there.

edit add: BUT you will have to test the Red/Lt Green for both switch positions: "Run" and "Start". It may be only "run", and a second wire will be start, and you also have to check for, and deal with, the inline resistor if it's present.

 

[Acgallen]

Does it look like this:

View attachment 106236

If so that's C102 and you can get ignition power there.

edit add: BUT you will have to test the Red/Lt Green for both switch positions: "Run" and "Start". It may be only "run", and a second wire will be start, and you also have to check for, and deal with, the inline resistor if it's present.

I was mentioning the circular grey plug coming from the engine harness. I do have the plug you mentioned i believe, as it should also have oil pressure and coolant temp wires with it too?

 

[RobbieD]

The round plug on my '84 is a 2-pin, and it does connect to the ignition module. In fact, on a 2.8 Duraspark conversion the round 2-pin plugs right into the Duraspark module.

Anyway, yes, the square gray 8-pin C102 is where the oil pressure and coolant temp wires are; Red/White for temp, White/Red for oil ('84 colors).

Not real sure on what differences there are, between the '84 and '85 wiring, but on a Duraspark conversion they seem to be fairly the same on the basics.

 

[Acgallen]

The round plug on my '84 is a 2-pin, and it does connect to the ignition module. In fact, on a 2.8 Duraspark conversion the round 2-pin plugs right into the Duraspark module.

Anyway, yes, the square gray 8-pin C102 is where the oil pressure and coolant temp wires are; Red/White for temp, White/Red for oil ('84 colors).

Not real sure on what differences there are, between the '84 and '85 wiring, but on a Duraspark conversion they seem to be fairly the same on the basics.

So in attaching the red/green wires together, the voltages changed in the EEC relay. As seen in the second photo, the yellow wires are constant battery voltage, the red/grn on the right side reads .55 v with the key out and 11.6v with key in. The other red green reads 0 with key out and 12.2v (battery voltage) with key in. Still not getting a click when turning the key, but it is changing with a key turn now.

 

[RobbieD]

You're using the '92 4.0 host truck's harness and EEC relay, too, right?

And if I read you right, you now have the original '85 Red/Lt Green wire getting a full +12V in ignition switch "run"; what about in "start"?

 

[Acgallen]

You're using the '92 4.0 host truck's harness and EEC relay, too, right?

And if I read you right, you now have the original '85 Red/Lt Green wire getting a full +12V in ignition switch "run"; what about in "start"?

Yes, all harness came right out of a 90-92 4.0 and relays.

It reads a full 12v in run and in just testing start, it read 10.5v while cranking

 

[RobbieD]

Assuming that you put the '92 power distribution center into the '85; pull the EEC relay out of its socket and test that ignition circuit at the relay, again for +12v in start and run key positions (don't worry about the 10v reading for now).

The EEC relay needs only two things to "click"- ground on one side of the coil, and +12v on the other. You're looking for the Red/Lt Green, and Black/Lt Green, wires underneath the relay for your testing.

If you're not getting power and ground at the relay socket, the problem will still be the wiring; if you are getting power and ground on the coil contacts then the relay is not working. I have seen corroded terminals at the power distribution box before cause relays to not activate.

 

[1984RESTOMOD]

Does it have gas

 

[Acgallen]

Does it have gas

Yes, plenty of gas. Its spark and no fuel injecting

 

[Acgallen]

Assuming that you put the '92 power distribution center into the '85; pull the EEC relay out of its socket and test that ignition circuit at the relay, again for +12v in start and run key positions (don't worry about the 10v reading for now).

The EEC relay needs only two things to "click"- ground on one side of the coil, and +12v on the other. You're looking for the Red/Lt Green, and Black/Lt Green, wires underneath the relay for your testing.

If you're not getting power and ground at the relay socket, the problem will still be the wiring; if you are getting power and ground on the coil contacts then the relay is not working. I have seen corroded terminals at the power distribution box before cause relays to not activate.

Wow i feel like a dummy. Thank you so much for helping me get there. The black green ground wire on the relay goes to a 2 pin plug (both ground wires). I did not have them grounded. Grounded them, relays clicked, truck started!

 

[RobbieD]

Good work!

And yes, I still do stuff like that myself.

Good luck; now go make it a runner!

 

[Acgallen]

Good work!

And yes, I still do stuff like that myself.

Good luck; now go make it a runner!

That is now seeming to be harder than i thought. Truck will start every time but wont go into high idle, just dies a second or 2 after initial fuel burn. I can get it to stay on a little longer with starter fluid and tapping the gas when it tries to die. Just replaced the IACV, tried 2 different MAF's, unplugged and replugged TPS (with no change). I wish i could post a video of it trying to run, but i dont think you can on this website. Its a brand new delphi fuel pump with brand new fuel lines AND filter. I want to also prefice that this whole engine setup (sensors, plugs, relays...) was working great the last time i used it (2 years ago). I was reading on some forums about the fuel pressure regulator, but that would be a strange thing to go bad. I know i currently have the firing order 1-2-3 / 4-5-6. Doing some research i believe its supposed to be 1-2-3/ 5-6-4 , but im not sure that would give me the problems im having. Unfortunately this is the last thing on the list get the bronco moving for the first time in 10 years. So close yet so far.

 

[RobbieD]

Probably be a good idea at this point to put a fuel pressure test gauge on the fuel rail port, and verify that the fuel pressure is within spec.

 

[RonD]

Yes, coil pack needs to be
3 4
2 6
1 5

Rewire it

All gasoline engines need to be Choked on cold start, fuel injection doesn't change that
So computer has the ECT sensor to tell it coolant temp, the colder the temp the more Choke is applied
ECT sensor always has 2 wires and is a 5volt sensor
ECT sensor data is what computer uses to set higher idle and richer fuel mix, i.e. Choke Mode

There is also a temp SENDER on the engine, 1 wire and 12volts, its for the dash temp gauge

They look similar but are not interchangeable

 

[Acgallen]

Yes, coil pack needs to be
3 4
2 6
1 5

Rewire it

All gasoline engines need to be Choked on cold start, fuel injection doesn't change that
So computer has the ECT sensor to tell it coolant temp, the colder the temp the more Choke is applied
ECT sensor always has 2 wires and is a 5volt sensor
ECT sensor data is what computer uses to set higher idle and richer fuel mix, i.e. Choke Mode

There is also a temp SENDER on the engine, 1 wire and 12volts, its for the dash temp gauge

They look similar but are not interchangeable

I rewired everything and it sounded better, but the truck wont stay on past initial fuel burn. My poppop and I were able to keep it alive soley running on starting fluid. Seems to me im lacking fuel, if i try to use the throttle it kills the engine quicker. I will try to get a FP gauge on it soon, what are the chances its Fuel pressure regulator related? Not sure what else besides possibly injectors.