Truck is a '99 silvo w/ 5.3. When truck is cold you need to prime the pump, then wait a sec then start it. However, if u shut it off and restart it 20 mins later it'll start up with one turn, if it's cold (sits overnight) and you hop in and turn the key to start it it will crank for a while, sputter then start or if u prime it, wait a min it'll start up. Truck has a new pump n filter. Any ideas I can look at next?? Thanks

 

put a fuel pressure gauge on it and see if it holds after the key is off. sounds like you might be slowly losing pressure...leaking inj, check valve in pump (i know its new), reg issue...Also pull the vacuum line off the reg with eng running and see if fuel "splashes" oout the vaccum port, those early trucks were bad about that. Although that was usually a hot start concern along with a rich code but check it anyway its an easy test.