Help! Truck has no power at WOT

[CIverson]

Truck worked fine this morning on the way to drop my kid off. Then Coming back it started. Power and everything is fine unless you push the pedal all the way to WOT. Nothing is wrong otherwise.



The engine loses all power you can hear it just shut off almost, like an instant idle. The turbo spools down, and if you keep your foot in the fuel, it backfires.



Go back to less than WOT and all is well.



Changed fuel filter, pressure is good, trans fluid is good and full.



I even tried turning my TST to 0/0 and still the same crap.



Only codes are 0606, 0336, which I've been getting since I got my TST. And 0483 which has to do w/ the cooling fan.



Help me out!

 

[jwilliams3]

What is your fuel supply pressure?

 

[CIverson]

A steady 19psi. I have a FASS.

 

[CIverson]

Took it for a drive to get fuel. First 5 miles, no problems. Then it started again. Even when I didn't go WOT.

 

[CIverson]

Thinking it might be the pressure relief valve since I have good pressure, and good performance until the throttle gets kicked down.



I cracked the banjo for it, then started the truck. Shut it off, and it was wet around that line.



I was under the impression that there should be no fuel coming from this. Does it mean my pressure relief valve is bad?

 

[drewRoberts]

I would say your high pressure valve has popped and your running into a lean-out problem.

 

[jwilliams3]

The valve could be bad sure.

Just because fuel is there does not mean it is bad though.

 

[CIverson]

The valve could be bad sure.

Just because fuel is there does not mean it is bad though.

Ok, I had read in another thread that it meant teh valve was bad.

 

[jwilliams3]

If I remember right there is always an amount that could/passes through it back to the pump/tank etc.

 

[CIverson]

There is a cascade valve also (on the pump) that regulates fuel to the pump for lubrication and such. There is also a valve that regulates the pressure to the rail.



The pressure relief is only supposed to vent excess pressure, as in the rail has too high of a pressure, and for safety needs to let it down. In theory it shouldn't reach this point, but with pressure boxes it may.



I don't have a pressure box.



Being that it is only supposed to pop off to extreme pressures, this is why I think it shouldn't be leaking any fuel out of it. Most posts here say that once the valve pops once it's not quite the same anymore.



My theory so far is that this valve is bad, and is letting go at normal pressures, dropping the rail pressure way down and causing my truck to not want to go.



I could be totally wrong. I just want to get it fixed or to know what is wrong with it.

 

[CIverson]

Anyone else?

 

[Cummins724]

My brother has an 04, and was having the same problem one time and tried everything, Turns out when he took it to the dealer, It was that the air filter got sucked through the intake tube. I mean crumbled like a pretzel, it took them 2 days to find the problem. At first the service manager said it was probably the lp or injection pump, etc. The truck ran perfect till wot, then fell on its face. Probably not the problem, but figured i would let you know. K&N Air intake cured that problem.

 

[p-Bar]

Eliminate the box out of the curcuit.

 

[tobaccogrower]

i second removing the tst then testing again. computers can be funny... . james

 

[CIverson]

Yes, I am going to remove it, just waiting for it to warm up a bit. Supposed to get into the 20's this afternoon

 

[steved]

Supposed to get into the 20's this afternoon

Are you sure your fuel didn't start to gel... that is classic symptoms of gelling fuel.



steved

 

[CIverson]

I wouldn't think so. I ran power service in it (just started using it the last 2 tanks).



It's been alot colder and I haven't had troubles and I always get fuel from the same station. Also, my fuel pressure has not changed one bit. I would expect it to get higher if the fuel were thick.

 

[CIverson]

Box is completely out. Same deal. Sometimes only at WOT, but after it happens the first time, it seems to happen quicker the next time I get on the pedal.

 

[CIverson]

Another update.



After removing the TST I decided to try and stay in the throttle after it looses power. W/ the TST it would backfire so I let off it right away.



Now I stay in the gas and the engine either stays at the RPM it's at or slows down a little on the RPM's and pretty much stays steady there (rough running though). The few times I did it. Sometimes it would pick power back up real quick then lose it. Sometimes it would just stay steady. Almost like it was being regulated to stay at that amt. of fuel.



Also, every time I take it for a drive it only kicks out at WOT the first time. Then after that it happens sooner and sooner in the pedal travel.

 

[smokejunkie]

Does the TST plug into the fuel pressure connector? I had a similar thing happen and my fuel pressure connector had come unplugged.