I need some help. New to this forum and have looked around but can't find the exact answers I need. I have a 86 f150 with a 302 carbureted (not sure of the motor year) and 4 speed trans. Parked it one day went to start it 30 minutes later. Wouldn't even hit. Someone has wired this truck up their way so it's all confusing to me. It cranks normal. Getting fuel. I poured gas down the carb still nothing. No spark not at the plugs not the coil wire. It has the dura spark II system on it. Pretty simple but I'm still stuck. Took the ICM off (blue harness on it) which wasn't grounded? Mounted on plastic fender well. But it worked until now. Anyways the bottom of it was melted out. Replaced it. Wired up the same. Still nothing. Replaced the coil. And the distributor (a 79 302 disitrubutor matched the one I took out of it). After cranking both the icm and the coil get real hot. They have the system wired up wrong but it worked before so why not not? Maybe put a new ignition switch in it next? Any wiring schematics would be helpful. Or if someone could point me in the right direction it would be very much appreciated.

 

My guess is they have 12V to the coil and the ignition modules are getting burned out - but that's just a guess, you will need to find some proper wiring diagrams and do some diagnosis to see what you have.

 

In the start position the hot side of the coil should have 12 volts. In the run position with the engine turning you should have around 7 volts.

 

Yes, bruno is correct, two voltages in two scenarios, I don't want to mislead you... do your homework here....

 

What Chris is saying is that maybe someone has wired it to have 12 volts in the run position which is bad.

 

Yea I can tell it's bad haha. I don't get how it has started fine the past year for me now won't.
This is where someone rigged it up and I just wanna find out the right way.. There is 1 wire (white/blue) coming from the ignition, hot in the on and start side. It was then hooked up to a wire ran to a fuel pump on the frame rail and has both the icm wires (red,white) on it also. That's gotta be too much drawing off that 1 wire.

 

Yeah, that might be a problem as well. I was running a wire to my choke from the coil and it caused issues with both the choke and the ignition. So find another key on source for your fuel pump.

 

Look up a Duraspark II wiring diagram, there are plenty out there... they're not all the same and there can be some minor variations depending on the configuration but they'll get you started and you can compare to what you have....