So i spent several hours today replacing header gaskets, collector gaskets, and installing the o2 sensor.

Took it for a drive to see if i could hear any leaks. Everything sounds good there.

But when i take off. The truck has a surging to it. I have noticed it before, but was more angry about my exhaust leaks. Now this has me confused...

I can take off shift in to second and if i give it say 3/4 throttle it will take off, then choke out take off choke out. Not like a complete dead cut out. But its a signififcant loss in power, the truck will still power its self along, but not very quick like. If i floor it the problem is worse. Now If i slowly feather the throttle down until its floored, it will continue to surge. Say about maybe 1/8th throttle though, it will take off like a bat outta hell, no surge at all, shift to second when i find the same "sweet" spot with the throttle it will take off again, shift to 4th it will pull for a little bit, but when i give it more throttle to accelerate it will start surging again. If i stop and rev the engine it doesnt seem to be surging, but i wont say its deffenitly not surging.

I keep saying surging because im not exactly sure what other word to desribe it.

Surging being, its got a quick burst of power, then it then very quickly the power will stop and it will be weak, then it will snap back to having power, jumping back and forth some times it will be 2 times in a second some times it will be 5 or 6 seconds before it will surge again.

So, im really confused as to what would be causing this....
Some one care to help me out?

 

What are we working with here.

 

oh sorry i forgot my sig is gone...

Its a 1995 f250 4wd a 351w and a zf 5 speed. It is EFI also.

 

Have you checked your fuel pressure? I had a weak pump that gave similar symptoms...

 

That was a thought... Another thought was maybe the TPS was goin bad or something...
Wasnt really sure, didnt feel like crawling all over the truck looking for the problem tonight, or ever actually as it is a big freakin truck. Would it make a difference if i changed tanks? Or is it the high pressure pump going bad?

Also what should the pressure be at? I would look in the manual, but i guess somebody found a better use for it, as i cant find it ANYWHERE...

 

Should be around 40 psi.

 

Ok well i havent had much of a chance to chase down the problem. But i got in my truck today, after my mom had used it to move one of the big mowers, and she had switched tanks, so im goin around town and i realize my truck is running GREAT! No stutter no surging, throttle response is MUCH better. So i dont think its the high pressure pump, if im not mistaken there is only one, and both of the in tank pumps feed to that one high pressure pump. Am i wrong on this... So this leads me to think that maybe the pump in the front tank is going out... Or could it be dirty fuel or something like that?i I filled up the front tank probably 3 or 4 times, cause i never knew how long i would be gone, so i didnt want 2 full tanks of fuel to waste away... Think it could be something in the tank or the pump goin bad?

 

Starting in 1990 they eliminated the in frame high pressure pump. Your in tank pump is your only fuel pump(one in each tank with dual tanks). Your in tank pump is likely the problem on that tank.

 

ah. i thought they both in tank pumps fed into 1 high pressure pump.... Alright thanks for clearing that up. I will check it out and see what happens...

 

i agree with 88n94 it sounds like your front fuel pump. that is if it never acts up on your rear tank.

 

Nope runs like a raped ape on the rear tank....