So, I bought '86 Bronco 302 EFI 4speed last year, and it has always had trouble starting when it's hot. It's to the point now that if you shut it off, you can't expect it to start without sitting for at least 45 minutes. When you start it when it's cold, it fires right up without hesitation. While it's running, it runs beautifully. No power loss, misfiring, anything. But as soon as you shut it off, it acts like the battery is dead. When you turn it over, it chugs really, really, reeeeeallly slowly. Sometimes, it won't turn over at all. Every once in a while when this is happening, it'll catch a second wind, and pick up the pace a little until it starts. Usually not, though. Once it has cooled off, it will fire right up. Again, without hesitation. No matter how hot it is, or how resistant it is to turning over, pop-starting it will always fire it right up.

I originally thought it had a bad ground that was heating up. Checked all the grounds on the starter circuit, nothing.
I then thought the exhaust manifold was heating up the starter so bad it wouldn't transfer power. I wrapped it in heat wrap (titanium) and ran it hard for a while. The starter was cool to the touch, but still wouldn't start.
So I replaced the whole starter. Nope.
I replaced the starter solenoid. Nope.
I replaced both the positive cables. Nope.
I replaced the battery and the terminal clamps. Nope.
I replaced the ICM. Nope.

I'm sick (and poor) from blindly replacing parts. It is a danger to drive, because if I kill it (which isn't hard; 3.73 gearing and 35" tires) or if it decides to die, I'm stranded there. I have to get this fixed.

Anyone have any ideas?
Thanks in advance!
Quinn

 

First thing I would do is try to find a code reader to see what codes might be showing up.

 

I have pulled codes. Nothing has to do with the starter circuit.
It pulled:
06

41
77

77
41

44
77
44
77

 

My '91 5.0 f-250 did this some years ago, soon after it started we had it in and a bunch of work done including the starter. But what i recall was even more of an issue was i was told one or more of the ground cables had broke or fallen apart. Either way we added in heavy gauge arctic grade ground cables between the frame and engine block, engine block and battery terminal, also between the frame and body. Since then i have had no issues even on the hottest days with the truck driven all day.

 

A continuity check will not be an accurate test of a connect or its ability to conduct power. Seems to me that you have a breaking or broken cable or a faulty connection.

 

Alright, I'll check all the grounds. Does anyone know where I can find them?

 

At the opposite end.

 

The opposite end of what?