Cummins 400 ISL loses acceleration randomly

[BobButerbaugh]

My 2002 Beaver Patriot Monticello with Cummins 400 ISL engine randomly will lose the ability to accelerate without stalling. It has happened 3 times: 1. started up in the morning and within 5 minutes, I lost ability to accelerate at 30 mph; then it stalled. 2. Driving for about 1/2 hour on route 95 in Virginia, I lost ability to accelerate going 65mph. When I slowed down it stalled (yikes!). 3. A mobile diesel repair guy replaced the transient suppressor and promised that would solve the problem. However, last weekend I started up in the morning and within 5 minutes, while driving down a moderately steep hill, I lost the ability to accelerate, when I slowed to stop, it stalled. In all cases, once I turned off the engine then restarted, it ran fine. Has this happened to anyone else? Any idea what might be causing the problem?

[Eric Maclean]

Bob
Off the top of my head I'd be looking at two or three types of problems.
1) could be air in the fuel but the fact you get an  immediate restart would likely illuminate that.
2) possible electronic or mechanical issue causing the ECM to derate and shut down ( how ever this is almost always accompanied by a fault code or two )
3) could be a possible voltage issue with the engine ECM  lose of ground or power to the ECM

After reading your other post about high voltage 16.3 volt warning on your inverter while driving I would be leaning toward a voltage issue with the alarm being intermittent it would point to alternator problem or bad or lose wire.

I'd start by checking your charging system voltage and from there go to ECM and engine ground's .
A lose of ground between alternator and engine and or batteries can cause an overcharge situation as well
Have you checked the engine ECM for fault codes?

Eric

[Dave Atherton]

Bob, sounds like you have engine speed up problem located at your foot pedal that is causing
problems. There is a 5volt sensor at pedal assembly that is going bad. On some motorhomes
this sensor or actuator can be replaced, than on some Monaco built motorhomes you have to
buy the foot petal assembly as a unit. Going deeper look around your foot pedal you will locate
Wires operating actuator ( there are 3 wires ) could have a loose or dirty or shorted connection.
My suggestion disconnect actuator wire and see if you are getting power all the time wiggle wire
for a short etc. again this is a 5 volt power. Dave Atherton Retired Cat Mechanic

[Dave Atherton]

Bob, back again it early and have not gathered all my thoughts, but first thinking about on thing but got ahead of my self. Let start over you have a common rail fuel system under high pressure and on
the fuel rail there is a return fuel pressure valve ( location on the middle of the common rail ) that
Valve is very easy to locate because its screwed in to fuel rail and is vertical  about 3 inches high with
a steel line connected to top of valve. This is a very common problem and a easy to locate and replace.
Dave Atherton Retired Cat Mechanic