The 2000 Blazer runs fine once started but when it sits over night it will not start took a hour this morning ,changed the fuel filter and can hear the fuel pump primming it runs fine after it starts even after sitting for an 8 hr day would the pcv valve have anything to do with it? any suggestions would be most appreciated .Thank You
Twisted

 

I doubt the PCV valve is involved. I would suspect a leaking fuel pressure regulator. Try this thread:
96+ Fuel System Diagnosis