When I get on the throttle hard my truck surges,then smoothes out when I back out of it. Fuel pressure is 15lbs idle 13lbs cruise 10lbs wot. I changed the fuel filter even though it looked fine, no water in canister. Boost tops out at 34lbs. No codes other than the ones I always have with my smart contoller that have to do with the tranny. Bill K said because I have a calif. truck the computer does'nt like the controller. The last time this happened was on the way home from B.C. after some upgades. I changed out the fuel filter which again was ok but she ran fine for the next 1500 miles. I'll check electrical connections tomarrow nite. If anyone has any other suggestions of were to look we're all ears.

 

My suggestion is to take the throttle through the procedure to allow the APPS to find zero again. You will find the APPS reset procedure listed under the 24 valve topics in the Tech Facts section.

If that does not solve the problem, then you should start thinking about the VP44 needing replacement. When the delivery port erodes in the injection pump, the same symptoms will happen, and it will get increasingly worse over time. Generally speaking, the injection pump does not just conk out, but slowly degrades until becomes erratic and then it will just conk out.

 

A defective MAP sensor will cause surging like you are describing. It is usually noticeable at 2000 RPMs and above. The MAP will cause fueling/defueling as it reads the manifold pressure.

 

Well I have to thank you for doing the leg work because my truck is running great.Oo. Oo. I really think it had more to do with the ground off my banks box being grounded to the fuel filter mounting bolt. I spliced a wire, soldered it put shrink wrap over it & ran it directly to the battery ground. I also took both ground straps loose at the block wire wheeled the bolts, washers, & block, cleaned up the battery termanals put the little fuzzy anti corrode things on. I tried everything this afternoon to get her to stumble 110mph & morepower left. Thanks again ToolMan Tim Taylor you rock. I'm posting this for others in hopes it will take care of their hesitation problem.