2000 4.3
My blazer always starts easily on the first crank (cold), but after running long enough to heat to normal running temp, turning it off, and sitting for 5-20 minutes, I have extended crank times. If it sits for 2 hours, it cranks on the first try.
Fuel pump was replaced, pressure confirmed to the test port, 60 psi iginition, 50 psi run hot or cold. Changed the fuel pressure regulator inside intake, with no change, and no noticable spider leaks.
Check engine code exist for faulty air pump, but no other codes. I have cleared and it takes about a week, to return, with no effect on the issue.
Any ideas on why this only happens after running would be appreciated.

 

Need to confirm what the fuel pressure is when this happens. Does it lose ignition?

 

Sounds to me like the starter is getting too hot causing the problem you are having. You might want to fab something up to block the heat. Start with something temporary to confirm, like a heat resistant wrap, and if it works fab up a heat shield for the starter.