Thank you all. Based on the suggestions give, I took the truck to my local guy, who listened carefully to all of the below, and then did his own research.

He checked the Service Bulletin, looked on Ford forums, and decided to wrap the starter with exhaust insulation.

His two hour drive testing confirmed that the truck would start when seriously hot, and in my own use, it has beef perfect since.

I really appreciate the support given here, and it is proof once again, that this Forum can solve almost any problem.

quote:

So, Ford has a problem with starter that when the engine is hot, it won't crank to start. There is a service bulletin, and it is related to the ground.

Does anyone have experience with this and how to fix it? I understand that a new starter isn't necessarily the correct answer.

This message has been edited. Last edited by: ArtieS,

Should be easy to check. Verify power to the main lug and solenoid while in crank. Most ford trucks have the engine ground connected right at the starter bolt, verify that connection is clean and tight on both ends. If that all checks out, its not uncommon for the windings on an electrical component to open due to thermal expansion.

I'm not familiar with the service bulletin. I had that problem with a 2017. It was not a grounding issue but a problem with heat soak on the starter itself. The eventual 'fix' was an aftermarket starter. A replacement Ford starter lasted about 6 months and failed in the same manner.

^^^^^ Thanks for the tip on the windings. So, it could be the starter and not the ground in that case.

quote:

Originally posted by bdylan:
I'm not familiar with the service bulletin. I had that problem with a 2017. It was not a grounding issue but a problem with heat soak on the starter itself. The eventual 'fix' was an aftermarket starter. A replacement Ford starter lasted about 6 months and failed in the same manner.

Do you recall which aftermarket starter you used?

What year is the F150, make it a bit easier to review starter options.

^^^ The year is important. For example, up to roughly 2005, the ground cable (and some other, smaller wires) connection is on the frame inside the right front wheel well - a location prone to rusting. For that matter, so is the starter location. I've seen the solenoid connections literally fall apart.



Do you know how to do voltage drop testing? It may need some long jumper wires and a helper, but no matter how odd the symptoms, electricity itself follows a fixed set of rules. Zero to 0.1 volts is good, 0.2-0.3 marginal, anything above that is bad.

Isn't "won't start when hot" also a sign of a failing crank position sensors?

For those who have asked, truck is a 2018 with 55K miles.

quote:

Originally posted by cas:
Isn't "won't start when hot" also a sign of a failing crank position sensors?

He specified "won't crank when hot" A failed CPS would not prevent cranking. Cam/crank position sensor failures are getting to be pretty rare on the newer (post 2010-ish) stuff. Much better electronics these days than the junk from the 90's and 2000's.

Voltage drop, as previously mentioned, is extremely important.
It is generally ignored because it is not understood.
If you don't understand OHMs law, you really need to start with basics before guessing what is wrong.
Most in here are antique people that really don't care about that stuff. They read and look for answers that they want to hear.

Stored history codes are important, here is a link to why, it's not your vehicle but the diagnostics still apply.

http://www.dewitzdiagnosticsol...powerstroke-diesel/#

Think I'd take the battery and have it load tested, if it's experiencing issues then overcoming any resistance in a hot starter could be a problem.

Those trucks have a lot of electronics between the starter and the button that initiates it so there are a lot of little electronics in the circuit from Button to PCM, Battery, relays, security fob etc.

Whenever I had similar issues on the F150 it almost always ended up being a 3 year old battery that wouldn't allow the starter to work.

Battery is brand new. Changing it out was the first attempt to solve this mess.

quote:

Originally posted by ArtieS:
Battery is brand new. Changing it out was the first attempt to solve this mess.

That's good, first step done, since it starts once it's cooled down you could put in a heat shield to deflect heat from the starter.

Some recommend the 5.0 Coyote High Performance starter M-11000-C50A it's a mini starter, Fords info says it's not F150 compatible but several people said they got it to fit right up.

Same people said they found corrosion on the bolt holding the ground cable to the bell housing, and that they found a lot more resistance using a meter when testing before cleaning it up.

That with the heat soak might be the issue, think I'd crawl under, undo the ground clean up the bolts and tighten down, in fact, probably go to NAPA and get a new ground cable and replace it before investing in a new starter.

quote:

Originally posted by rizzle:

If you don't understand OHMs law

Artie is a lawyer.

Sounds like the starter is heat soaked.
Wrapping the exhaust pipes near the starter with exhaust shileding may do the trick,

My 78 corvette was doing this so I wrapped the starter in a heat shield blanket and replace the old copper clad aluminium terminal wires with pure copper.

I had a 70s something Caddy that had the same problem, ground cable broke in my hand when I was working on it. It also green from corrosion like the one shown.

I check in on this F150 forum daily. Lots of knowledgeable folks. You might consider this option : https://www.f150forum.com/register.php

^^^ Thank you all for the great information, and thanks KH for the reference to the F150 forum.

A

Update and thank you in first post.