Hi. You've got a problem with something on the engine that is setting a trouble code. When certain problems are seen by the engine controller it will put the engine into a limp in. It will bring fuel control back to the idle governor until it thinks it safe to procede. There are some codes stored in your Cummins engine controller, the first step is to get these codes. Almost all parts stores will check for codes for free now. If you can run by a parts store and come back and post the codes here I can tell you what to do to fix your problem.
what came up wasnt a code per say, it read fuel injector timing curcuit malfuntion, of course the truck was running fine, never does it running around town, yesterday was the first time it did it unloaded, we were running interstate but no load, in thepast its only done it while running interstate speeds hauling a heavy load say 8000 lbs or more throttle position sensor hasbeen replaced with no improvement
Ok, that's p0216 injection pump timing failure. There are only a couple things that will set this code. the first is low transfer pump flow. If you starve the injector pump of incoming fuel it will set this code. If the fuel filter is plugged or the transfer pump weak or not working, it will set this.
Outside of fuel delivery, the only other thing that can cause this is a failed injector pump. Its not uncommon to replace both pumps at the same time for this. The only thing that lubricates and cools the VP44 injector pump is the incoming diesel fuel. If you starve the pump of its fuel, it self destructs pretty quickly. Many 24 valve owners put a gauge on the inlet of the injector pump so they can monitor the pressure so they can shut down before doing pump damage.
If you find your transfer pump is ok and the injector pump is the problem, its not a bad idea to replace the transfer pump along with the VP44. Its cheap assurance that you won't ruin your new injector pump.
ok i did a volume fow check on the transfer (lift) pump and got 56 oz of flow in 26 seconds, well within limits. also changed the fuel filter while i was there but the old filter looked pretty good. the problem isvery intermentent,usually i have full power so i have doubts that the injector pump is the problem, i havent run a checkon the injector pump i feel its god but could run a check (pressure?)on it if u told me what to do,is there any sensor that could be malfunctioning intermintently that could be sending a false reading? sorry it took me so long to get back to u and i REALLY apriciate your help with this. my truck is my paycheck so it really is important to me to have it running right.thanks
If you have good flow to the injector pump the only possible remaining problem is the pump itself. There are no other checks or test that can or need to be done. You can rule out mechanical pump timing. Its gear to gear, no chain. If the gears were not in time (impossible) the truck would not start anyway. If the fuel volume to the pump is ok and it sets this code you need a pump. Its actually very common on the VP44 pump.