I have been fighting with this issue for a couple months now, it fires with no hesitation when cold but if I drive it and let it sit for an hour it will just crank and not fire. The truck has 180,000 miles, injection pump was changed 6000 miles ago, injectors are original, fuel filter is new, mechanical lift pump has 6000 miles also. Does anyone have any insight?

 

The main positive from the battery down to the starter is in "as new condition"?
The starter motor and engine are turning over at sufficient speed when warm?

 

The engine sounds like it’s spinning over quick enough, but I could be wrong, I do believe the battery cables are the originals, I will put a new cable on, sometimes it seems like the starter is powering down quicker than it should(starter is 1 year old, as are the batteries).

 

Wondering how you've made out?

 

I changed out the original cables with some AC Delcos, it definitely sped up the cranking but I still have the same problem and it’s getting worse, now after ten minutes of the truck being turned off it will just crank and not start, I seen my mechanical lift pump was wet when I was under the truck so the plan is to change that out today along with the rubber hose connected to it. I’ve also poured cold water on the injection pump and that didn’t do anything.

 

I changed the pump along with a short hose, it didn’t make a difference. Injectors have 180,000 miles on them, would they cause this problem?

 

I had something similar happen to another yruck i fixed urs ago and the fuel shut would work finevwhen cold and truck would run fine until he shut off. The fuel shut off would close but wouldn't reopen when it was hot. Once it cooled down it would would work. I don't know if you could accurately test a intermittent problem on those. Maybe check around and see if you could get one reasonably. But don't use anything aftermarket . I know thats preached alot on these . But I'm here to tell you. You will pull ur hair out if you don't use A/c delco parts on these. Which I'm sure you have seen this b4.

 

I fixed the problem, it was the starter, I ended up upgrading to a gear reduction 6.5 starter, wow does she turn over fast now.