Thank you, I will change the fuel filter first and will check back again with you guys.

 

i have a 2004 4 door 4 WD 4.3 and is doing what you said,it will start fine most of time from cold,drive around to couple places then no fuel pressure when crank-i checked with gauge one time in driveway when wouldn't start-so i found crank couple seconds turn of for about ten seconds try again so far will start after few attemps.It is a fuel pump from advance,second one,people say go with better brand,i think that is good idea.Runs fine after starts,may swap with horn relay just to see if any difference.

 

my 2004 blazer seems to have lazy fuel pump,sometimes won't start up after drikve somewhere.RUNS FINE AFTER STARTS.