I have 2001 cummins 4x4 6 speed with 172K on it. I have had this truck for 7 years, upgrades are quadzilla adrenaline, k&n, straight pipe, air dog II. About a year ago I thought I had a water issue driving on a 1400 mile trip on interstate 40 my truck started jerking at around 55-60 mph like it had water in it. Everything would go dead and then pick back up, nothing of consistency, let off the throttle and then back on it would respond then start doing it again bucking and snatching. It got so bad I had to turn chip off. I put RPPF fuel treatment in it and it seemed to clear problem didnt have any trouble with the rest of trip but every now and then it seems to do it on long steady driving with accelerator at a constinent position past 55 mph. I did replace throttle positioning sensor before this because I was getting a code to replace it. The problem has came back now a year later but seems to do it more when I drive on intersate and start gettting around 70 mph, it gets so bad it wont let me go aboe 55-60 mph on interstate. I have no codes showing up. I have replace filters drained fuel tank, unhooked quadzilla chip and still does it. The VP44 was replace 5 years ago but I figure if it was that I would get a code. The injectors are stock and have never been cleaned except the additives sold to put in fuel. Anybody with some recommendation would be of great help.

This sounds like it will be a bit tricky to diagnose. I think I would try immediately checking for codes the instant the engine acts up even if it means pulling off to the side of the road on the way to work. Another thing that comes to mind and is very unlikely, what condition are the truck's batteries in?I recently replaced my OEM original batteries after almost 11 years. They would still start the truck and worked OK but the voltage disparity between each battery or cells within each battery must have been causing problems as my truck was smoking like hell and just seemed really sluggish compared to what I remembered in the past. As soon as I replaced the batteries, the smoking immediately stopped and the engine performance was back to its old self. This may not be the case for you but if your batteries are old or gone bad, they may still start the engine and performe enough to get by but I would think a sudden surge or drop in voltage or an intermittent short could wreak havoc with the truck's systems. Might be worth a look.

This sounds like it will be a bit tricky to diagnose. I think I would try immediately checking for codes the instant the engine acts up even if it means pulling off to the side of the road on the way to work. Another thing that comes to mind and is very unlikely, what condition are the truck's batteries in? I recently replaced my OEM original batteries after almost 11 years. They would still start the truck and worked OK but the voltage disparity between each battery or cells within each battery must have been causing problems as my truck was smoking like hell and just seemed really sluggish compared to what I remembered in the past. As soon as I replaced the batteries, the smoking immediately stopped and the engine performance was back to its old self. This may not be the case for you but if your batteries are old or gone bad, they may still start the engine and performe enough to get by but I would think a sudden surge or drop in voltage or an intermittent short could wreak havoc with the truck's systems. Might be worth a look.

I have replaced batteries about a couple of years ago and cleaned grounds as well. I can have them checked out for sure to start with the simple things. I got a buddy with a Genisus can tool he said he can read all the codes and check all the sensors while driving so I am gonna try that as well.

You should be able to check your own codes using the 3 keying trick. Trucks that are 2000 through 2002 have this feature although some 2000 models don't always work.

The key trick does not work on all of them. it seems to on the 02's but the 00 anthe 01 are hit and miss. if you try it you should see p done twice. If you only see p done once it is reading only one computer. The codes you get with this method are not always all of them either.

I had a snap on machine monitor the injection pump , it showed fuel solenoid shutting off in injection pump. So I guess I have a bad vp44.

I had a snap on machine monitor the injection pump , it showed fuel solenoid shutting off in injection pump. So I guess I have a bad vp44.

Unfortunately it sounds like yours is computer related. "Dead Pedal" is very common with the vp, I had the same thing on my former 2000. Nothing can be done except change it out.

Unfortunately it sounds like yours is computer related. "Dead Pedal" is very common with the vp, I had the same thing on my former 2000. Nothing can be done except change it out.

i dont have dead pedal, i was just wondering if anyone knew if that fuel solenoid inside vp44 is controled by the transistor that is inside vp44 computer and by changing that transistor it would fix random serge problem that is so hard to diagnose.

"At steady highway speeds it cuts on and off" is what you stated earlier. That is exactly what mine would do when it went bad. Ive never heard of any available parts that can be purchased for the vp.

"At steady highway speeds it cuts on and off" is what you stated earlier. That is exactly what mine would do when it went bad. Ive never heard of any available parts that can be purchased for the vp.

go to youtube or type in google transistor change on vp44 most of driving issues are cused by it, i think. at least is what i heard,

and some times there is no codes whed this transistor fails, im just thinking out loud:think: