my truck is acting stupid

[rip van sparky]

Hey folks, my truck is doing some disconcerting stuff. For the past few days while coasting in gear, my truck has been surging, kinda violent like. It's like when your truck is in first gear and you stab the accelerator for a split second. It idles fine when the clutch is disengaged and runs fine when there is even a slight load on the engine, as in just maintaining speed on flat ground. It's just when it is in that sweet err... not so sweet spot when I am giving it just a slight bit of fuel to keep the engine from braking the truck or when the engine is holding the truck back a little. It does fine when normal engine braking to lose speed such as downshifting to slow the truck. So does this mean that my IP is shot and that I had better get a turbo IP to go with the turbo that I am getting from towcat , or is it something far less beneficial?

On a side note, I picked up a superduty intercooler on friday for $125 and the local jegs has mandrel bends reasonably priced that I can make the plumbing out of. Well, thanks for any advice.

 

[69oiler]

hate to say it but i vote IP. i had the same symptoms on my old boss's 7.3. i changed the IP and it solved the problem as well as made up for lost power.

what's happening is the internal timing of the pump is going willy-nilly. light steady throttle is when it happened for me. it will get worse and happen in all throttle positions eventually.

 

[DeepRoots]

before condemning an IP do a check for air and fuel line restrictions.

 

[Petri317]

I had the exact same symptoms with my truck, although out of gear I could also feel it idle a little bit rough and surge. It was surging upon deceleration. I replaced fuel lines, injectors, checked everything I could think of. Turned out it was the injection pump. And mine was a year old rebuild!!!

Check out the thread regarding the issues my truck was having:
http://www.oilburners.net/forums/showthread.php?t=16590