I have a an 87 F150 with 5.0L engine. Starts just fine when cold but when the engine warms up to operating temperature, it will not crank until you let it sit for about 10minutes. It sounds just like a bad battery in that it will just barely turn the engine over. I have seen some posts that would indicate it might be the starter itself. I have taken the truck over to the local parts house and they have a portable "test set" that checked the battery, alternator, and starter and declared them fine.

My question is this--- Could a starter be "breaking down" and getting hot to the point it is pulling too many amps where the battery can not turn it over.
BTW- When this occurs, it can be jumped and started.

If so, How the heck could you test that and confirm this problem...

 

I had this same problem with my bronco 2. I had a cheapo battery terminal clamp on the end of one of the battery cables. I changed it with a better quality one and I really cleaned wire and the battery terminals good and so far it seems to start fine.

 

If you can, Visually inspect all cables for sheath cuts, corrosion (green stuff), etc., then take resistance readings end to end on each of the cables when cold and again when hot. If the resistance changes appreciably (5% or so) change out the cables.

Bets are the ground cable is corroded at the midpoint frame connection. This will cause a "bad" battery, starter, etc., problem.

REPLACE THE Cables with 2ga cables. Use 4 separate cables 2 for positive, and 2 for ground. get the ground as close to the starter and insulate it from the exhaust as much as possible. Use di-electric grease on all connections to retard corrosion.

You'd be surprised at how much better everything runs with new cables.

 

Very similar problem, 1991 E350. Replaced battery, cables, solenoid/relay, and 3 different starters, even got those race car thermal wraps.
STILL HAPPENS!
Cranks fine when cold, starts right up, drive it for 10 minutes or more, shut it off (like at gas station) and then it almost doesn't crank, real slow like a dead battery. I've learned to keep the key turned, (rather than back off like you'd want to do to save the battery), it will crank extremely slow, with a few hesitations or "no cranks", but then will get past the slow and start to crank faster almost like it would when cold. (minus the recent drain on the battery) That's how I start it now, but I always feel like I'm real lucky if it starts.
Please HELP!

 

I've learnt after a long research that the main reasons for this problem are:
(All the above mentioned by other users)
-Tired battery (not enough amps)
-Bad starter
-Bad cables
-Ground
-Timing
I had the same problem a while back! New everything (3 starters too). I once spoke to someone who told me to ground the starter at the chassis, he said this extra ground would help, sure enough the problem disappeared. It started doing the same thing a couple of weeks ago but I'm sure it is a bad cable this time. I hope it helps.
A. Moreno.

 

Thanks for the reply! Someone mentioned timing to me once, saying if it's too advanced this will happen. If that is the case, would it do it only when hot? Or all the time?

Last starter replacement they ran a brand new ground to the negative on the battery, I should suggest the second ground maybe?

Thanks again?

 

My '88 has been doing this since I bought it and it done it to the previous owner. I was about to post it when I saw this post. I've tried everything on the list and it still won't start when hot. It sounds like it has pressure against the pistons. It lets out a little "pshhh" when it does start to turn over. The previous owner bought the truck new and he took it back to the Ford garage where he bought it from and they told him it wasn't releasing the pressure from something. He couldn't remember exactly where they told him it was coming from. I wish I could get mine fixed. I also have other problems I'm about to post.. Good luck TerryW....

 

I hope this link to another discussion sheds some light on your problems. I found them quite helpful at the time I was having the same problem.

https://www.ford-trucks.com/forums/2...ont-start.html

Apparently everyone fixes this problem by different means. I guess there really are many reasons causing the same problem on our trucks.

Last time I had this same problem again was a year ago or so, my mechanic who is a genius, told me that was the battery this time (with no hesitation)... and BINGO that was it!