Help!!! my truck has been running thenit starts to stumble like there isnt enough fuel and dies, but the fuel pressure alwasy spike when this happens. My idle pressure is 40-45psi and cruising is 39-42psi. It spiked all the way to 80psi as it started dieing!!! and it did this about ten more times as we tried to make it over the pass into Reno, we ended up turning around and heading back home and the truck seemed to run fine till about an hour later it did the same thing and continued to do it about 6 more times. The thing that has me stumped is the water in fuel light always came on, but not till after the truck died, also the truck would basically start right back up after it died (water in fuel light was still on). Plus it sounded like it was missing alot of the time and when i would go to restart it i had to pump the throttle to start it back up. We eventually replaced the lp because i had an extra and we did have any problems all the rest the way home(1hr drive) but im not convinced, any ideas????

jason

 

Okay so i took it for a short drive today, up some grades and back home(added some seafoam to the fuel to help dry up any moisture in there) and it ran fine, but it sounds funny to me, i have two 6inch stacks and the exhaust sounded really "poppy" to me under any load, it didn't sound exactly right, infact when towing before it never sounded like that?? what could it be???


jason

 

Your fuel pressure is too high like the overflow valve is bad or the return hose is kinked.
Normal lift pump specs are 17 - 22 psi at idle and 25 - 35 psi at 2500 rpm (no load).
Not only can high pressure blow out internal injection pump seals and even crack open your fuel filter but if the return is stopped up there will not be enough upper injection pump lubing/cooling.

 

Thanks for your input, when i first put the truck together my fuel pressure was at 20psi at idle but when i hammered down in it, it would drop to zero, so i asked some fellows on here about it and they said that 40psi at idle was okay, since under fuel throttle load it would still drop to about 15psi. so i have had it at 40psi for two years now, no leaks yet

 

Something is wrong then and may have deteriorated to your present problem.
I'm at about 350 hp, idle at 25psi, 35 at higher rpm but never drop below 20psi even towing 18,000 lbs up a 6% grade with 35 psi of boost.

Could be a kinked hose, one of your three filters plugged up or weak lift pump.

 

Well i adjusted the overflow valve which was kinda stuck and i now idle around 20-25psi and cruise at 37psi if i hammer down it wont drop below 20psi. So now my question is my exhaust sounds real poppy when towing up a grade and it don't sound right, without the load it runs fine, but something sounds off plus my engine temp starts getting hot if im pulling a grade, my egts will go to 1200* and i gotta let out a little so they wont pass it, im boosting 16psi and running 2000-2300rpms. It doesnt seem right im only in valet mode (230hp and 520tq) but my truck always gets hot!!! any ideas???


jason

 

There isn't much that can go wrong with these engines.
Perhaps your timing has slipped?

 

I guess i'll have to check that, but ive adjusted it many times and its never slipped, nor has it made the engine run cooler, no matter what i set the timing to, my motor gets hot goin up long grades, mostly when towing but even empty it'll start to get too warm i didn't mention this earlier but i have 3.07s in my axles(not that i wanted them) they are stock for my truck, and i run 33inch tires, would that make a difference??? i dont run up hills in OD and sometimes i'll unlock the TC so i get a couple more rpms which tends to help cool things down, but never enough


jason