i was going to say it Could be the fuel pump drainback check ball, since you said it loses pressure over time. but since it fired right up after it lost pressure... idk... this is a toughy

 

Yeah I was thinking before that it seriously could be the fuel pump but the chances of it getting better all by itself and then coming back a year later but worse is unlikely. Possible, but unlikely. I just don't know anymore but whenever I can get my tools here I'm gonna drop the tank and remove the fuel sender to take a look at everything and see if there is anything obvious wrong with it. I haven't really gone through this thing since changing the water pump gaskets last winter so I haven't checked any of the fuel lines or anything. "But", I did check all of the fuel lines and evap lines/hoses last year when this problem was so prevalent and didn't find anything wrong.

I just don't know anymore! *shoots self*........

 

Alright guys, I changed the fpr and filter about an hour ago. Just checked the fuel pressure at the rail while running. At idle it's sitting at 49.5psi and at both 2,000rpm and 4,000rpm it is pretty much the same. I shut it off and it dropped to 49psi even and I'm gonna check it at 15 minutes of sitting and again at 30 minutes of sitting. It's starting and running fine. Test drove it and seems to have a little more throttle response like the last two times I changed the fpr.

I have a wierd question though. What does it mean when your fuel pressure gauge goes up very slowly after you turn the engine off? I can't here the pump going if anyone is wondering. Went up to about 56psi when I went out to check it after it was off for 15 minutes. I bled it, turned it back on, reved it up a little, let it run for a minute, and shut it off. Same thing happened. Went up from 49psi at shut off to 50psi after about 30 seconds. Is it possible my guage is messed up?

After I tested it the first time I shut it off and checked it and it was at 49psi. I wanted to see what time it was on the truck's clock so I turned the key to the on position not thinking about it and ofcourse the pump primed and the pressure went up to 56psi. I turned the truck back on and it dropped back down to 49psi. Ya'll think this screwed the gauge up?

 

Na. That sounds normal. The pressure is regulated by a check valve inside the pump when the motor is turned off. When its running, the pressure is regualted by the FPR and how much voltage the computer sends the fuel pump.

 

Someone on ls1truck.com told me the fuel pressure is too low so I wreckon I'm gonna end up having to replace the fuel pump before it is all said and done. Ain't got the money for that right now though. Guess I'm gonna drive it and just hope the parts I replaced fix my problem.