My buddies 2002 cummins runs fine up to 20mph then it will lose power. You can put the petal to the floor and after about 10 seconds it will take off. Then it will run fine until you stop and start off again. I does idle good and has no smoke. He has no mods. 78000 miles. THANKS ED

Any codes on the odometer? when you say pedal to the floor, after 10 seconds it takes off, is it revving up, like a slipping TC or trans, or is it more of a dead pedal, where nothing happens at all, and then it goes? If that's the case, I'd pull the codes, and they should tell you either a bad APPS sensor, bad VP, or bad lift pump. If it's not a dead pedal, and the engine is revving up, but the trans is playing catchup, I'd guess something in the trans is worn out.APPS and VP should be throwing a code on the odometer, with the key trick.

Dennhop pretty much got it covered I would check error codes and see what pops up.

It is a standard trans. it acts like the turbo is all of a sudden coming on. We changed his lift pump this morning. After changing the pump we drove it about four miles it has 17 psi at the vp when we got back it is showing 0216. Will changing the lp throw the 0216 code ? THANKS ED

It's been a while since I dealt with a VP truck, but IIRC, the P0216 code is not one you want to see...I want to say it's the VP44 timing error...edit: and unfortunately, if I'm correct, changing the LP will NOT fix the code. Only changing the VP44 out.

Basically the P0216 code is a wear code from lack of fuel pressure. The timing piston wore out and now doesn't respond to commands for advance timing. When the ECM commands for more advancement it has a certain amount of time to respond but when the VP44 doesn't hit the mark in time then POOF! P0216 code is set. Usually low pressure is main cause but all fuel lubricity is also a secondary cause that causes the wear issues. Bosch states fuel must be below 450 HFRR score to pass and US diesel fuel is typically ~520 HFRR which doesn't make the grade.