Yea i jumped the gun on it after about 60 miles of driving it started to do the same thing all over again. I've got the blue spring upgrade comming in tom but i doubt it will help im not really sure where to go from here?? Do you think it could possible have anything to do with the hpop?? I think im going to drop my tank this weekend and make sure all the seals and dip tube and all is good on it. Im really at a loss.

 

Yeah I don't see the spring helping, but it's possible. Your issue seems intermittent, so if your factory fuel pressure regulator spring was weak, it would be weak all the time, not just part time. Fuel pressure gauge still fluctuating? Can you test the voltage going to the pump when it's running and make sure it's getting the appropriate voltage?

 

Honestly i wouldn't know how to test it. Yea it is still fluctuating but not quite as bad as before yet it seems like the more i drive it the more it fluctuates.

 

Just a simple multi-meter set on V (something like 100V setting) then just the red and black plug, one on each wire going to the pump to get a reading. The prongs should be sharp enough to poke through the wire insulation.

I'm not sure what else would cause it to fluctuate so much.

 

Ok i'll give it a shot.

 

Bmoore, check this out. Read it all, but pay attention to the very last post.

Erratic fuel pressure - Ford Truck Enthusiasts Forums

We may have been pointing at other things because of how the truck was running. I would find it very coincidental if the truck ran like poo while it was doing this, and they weren't related, but hey anything is possible right?

Also, have you tried scanning for any trouble codes out of curiosity? Even though the check engine light isn't on, it doesn't mean there are no codes...

 

Yea i thought of the gauge thing and just installed an electric gauge. But that sounds exactly like what im going through minus the truck still running like crap. Since i have installed the new fuel pump it doesn't take long for the truck to start running like crap at all. But all i have to do to correct the problem is to either rail on the truck for a few seconds and clear all the air or pop the cap on the secondary filter and everything clears up for a few miles. Im going to install the blue spring today and see how that goes. I have checked for codes and dont have any at all. Maybe it is two separate problems but i cant see it especially for the fact that when i clear the air out of the system it runs great.

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Do u think that it could possible be this "There is a quick connect fitting on top of the pick up tube assembly directly on the top the tank. I had a truck that had been fueled off a dirty in bed tank and the screen on the pick up tube was so obstructed the pump was pulling air in past the o rings in that fitting. All the filter o rings are on the pressure side so don't waste time with those." Thats what a guy on another forum is saying.

 

It could be man, hard to say, not exactly a common issue.

Have you checked the fuel filter cap on the frame at all? I've heard of those not seating properly causing similar issues too. They could still be sucking air on the pressure side, it's called the "venturi" effect.

What about the banjo bolts in front of the heads? Might be worth pulling those too and cleaning them out, heard of rare cases where those can be clogged with debris.

Have you ever run any biodiesel in your truck? I know some of the earlier tanks had issues with delamination, where the coating inside the tank fell apart and started sending debris through the system.

Just throwing ideas out... you may have to pull the tank though...

 

Mdub707 i think u were right i had two separate problems. I have done the blue spring upgrade and replaced the fuel pump and installed a new fuel pressure gauge and i now have a very steady fuel pressure. But i still get a rough running truck at idle and going down the road every once in a while, when i do get it if i stomp on the gas for a few seconds it acts really muffled and sluggish and then all the sudden it snaps out of it and runs like a champ for a while and then the problem starts all over again. Im leaning toward the icp sensor now any advice??

 

Maybe im thinking too simple, or missed something above, but did you check your filters? I can always tell when my filters are getting close to change intervals, because the truck will run a little lopy, and my fuel psi wanders. Sorry if this mentioned above somewhere.


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