ISC350, bucking under load/acceleration & speed limited

[Agent White]

Yesterday, coming home from a trip, my 2003 American Tradition (Cummins ISC350) started "bucking" or "jerking" whenever accelerating or going up a hill (engine load). Also, I couldn't get the speed above about 60 mph. When I slowed to 45 mph on flat highway, it was OK. I started getting an engine check light just before arriving at my garage. I did not find any relevant troubleshooting direction from the engine manual. Any ideas what it is?

[Agent White]

Yesterday, coming home from a trip, my 2003 American Tradition (Cummins ISC350) started "bucking" or "jerking" whenever accelerating or going up a hill (engine load). Also, I couldn't get the speed above about 60 mph. When I slowed to 45 mph on flat highway, it was OK. I started getting an engine check light just before arriving at my garage. I did not find any relevant troubleshooting direction from the engine manual. Any ideas what it is?

[gizmo]

try changing the fuel filter.

[Mike Canter]

If it run ok at a constant speed and only has a problem at wide open throttle under load then I agree with Gizmo in first changing your fuel filters.

[tom wilson]

lift pump putting out low pressure. cummins run it on their dyno and found the problem. replaced under warranty.

[Dave Fernandez]

Hello & Welcome Agent White:

You might also want to look at the U-Joints because they can cause a bucking problem if they are going bad.

[PeteB]

I had the same problem a few months ago and a fuel filter change solved the problem.

Pete

[SargeW]

On an 03' you are going to have a VP44 Bosch fuel pump. They are nortorious for failing, and that is usually how they start. I hope that it is a fuel filter for your wallets sake. Also check the lift pump that supplies the VP44. If it is failing it will kill your VP44 quick. At about $1200 for a new VP44, you don't want to run it at all until the problem is found.

Sarge