This forum is great, saving me a lot of guess work. Anyway...I drive a 95 Jimmy w/ 4.3ltr. synonymous with the full sepctrum of Blazer problems and this is my most recent. I have had an issue with the fuel pump not priming unless it was cool outside, or if the engine had not yet been run. I thought it was a fuel pump problem but decided to try some BG 44k before I spent the time or money.
Now, while the pump usually primes, I cannot get the truck to start. I have always had a rough starter, but I checked the grounds, and the voltage going to the starter and they are to par. The fuel pump whines, I turn over the engine and it simply won't take. Almost as if the fuel pressure is lacking only after I crank. I will probably remove the upper plenum and attempt to clean out and inspect the spyder and area near the fuel intake. Still what doesn't make sense to me is that once the truck starts it runs like a champ. Never any stuttering or rough idle. I have also inspected the lines and relays to the fuel pump which have also checked out OK.
So far, my only other thought is that the fuel pressure regulator has had it's day and I need to replace it. Any suggestions would be greatly appreciated.

 

I don't know the answer, so I'll just throw out an idea.
It seems to me that there should be a check valve in the fuel pump to maintain some residual fuel pressure. If the valve wasn't working , you would have a longer time cranking to get the fuel to the engine.
Do you have a fuel pressure tester?

A fuel system that drops more than 14 kPa (2 psi) in 10 minutes after being relieved to 69 kPa (10 psi) indicates a leaking fuel pump check valve

 

I don't have a Fuel pressure tester but, I can talk to some of the guys at work and hopefully someone should have one. Otherwise, I am pretty much in the dark. Hopefully when I open up the upper plenum I can get some better ideas about the obvious cunundrum. Thanks for your help.