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duttch1 · 03-28-2023, 11:05 AM

Hey all, new to this forum, new to this RV. I have a 1994 Oshkosh with 5.9L Cummins pusher, 6 speed Alison. I believe it's Ford frame based on steering wheel/column and key. It had not been started for several months. Charged engine battery, had to use ether to get it started. Once running, purred like a big Cummins kitten. Then, without any one at the wheel, the RPM's shot to 2500. I immediately shut it off, waited several minutes started it up and after a few minutes, same occurred. This seemed to be part of the governor linkage making this happen so I disconnected it and drove it home as I had just purchased it. Driving it home, it had no power. I couldn't hit 50MPH, flat road, pedal to the floor. I've read lots about ECM, intake sensor, throttle position sensor, fuel overflow valve. I have not been able to locate a throttle position sensor, it does not appear to have an air intake sensor (the plastic elbow on the Cummins intake where this usually is has a fitting and a plug in it, no sensor, no empty wire harness). I have not been able to locate the ECM in the engine compartment, under the dash or in the front hood area where the Alison control module is. I have not yet tested fuel pressure but it's on my list. I'm hoping someone much smarter than me can help me save time, sweat and money. Thank you in advance for any info.

153stars · 03-28-2023, 08:39 PM

Pretty sure that age has mechanical injector pump.
Does it have King cruise control unit. Take and post a pic of cruise control switches.
Remove a hose connector out of air outlet of turbo to look for oil to be safe.

duttch1 · 03-30-2023, 02:04 PM

Hey 153stars,
Yes, mechanical injector pump I believe to be the P7100. I've attached requested pics and a couple others.

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153stars · 03-30-2023, 11:16 PM

I don't recognize the cruise control as Kingcontrol . The only switches I've seen for those were more of an add on system with a small panel. I have brochure owners manual and some wiring diagrams for Kingcontrol but my MH came with optional M11 Celect electronic injection. But all the books and wiring diagrams for both motor/trans oprions.
Sadly your post has not picked up more help. Maybe search p7100 over speed idle. You should be able to see if the throttle is moved or sicking enough raise idle 700 to 2500rpm.
The lack of power is typical of plugged fuel filters first. Check/change old air filter you don't it to collapse . Check the boost side of boots from turbo. Fuel solenoid not opening 100% can cause lack of power.

RealNiceTent · 03-31-2023, 12:38 AM

duttch1, 153 stars is correct your 94 Bosch P7100 fuel control system is 100 percent mechanical, there is no ecm to locate and there is no electronic control of the P7100 fuel injection pump, only the fuel shut off solenoid is electric and that can be replaced with a mechanical cable control.
You said it goes to 2500 rpm without any input and disconnecting the governor linkage stops this, I believe that you are actually disconnecting an auxiliary throttle linkage such as a cruise control, the governor should be completely internal on your pump. Can you repost the picture of the pump and linkage with what you disconnected circled.

Dave

153stars · 03-31-2023, 05:22 AM

The King cruise is an early version of fly by wire. Do you have a throttle cable from the pedal. It would not be out of realm of possibilities of cruise that also works in conjunction with a cable or air throttle. The "P pump" (use term in Google searches) was on so many cummins there should vids and info on normal mechanical linkage and idle stop adjustment, to see if it hits the stop. I believe the governor springs play a role also in idle. I would be checking for free movement and return for all the linkage items first.
No real answer but started to poke around.
https://www.justanswer.com/rv-motorh...fo-cruise.html

Roy_johnston · 04-01-2023, 01:24 PM

So I have the same chassi and engine as you do. I suspect you have an Oshkosh chassis, as does chassis out the ford gas 460 in them I believe .

Yes your 5.9 is all mechanical m! That’s great news actually. I tuned mine from 230 hp, to 350hp super easy. Contact Power Driven Diesel out of Cedar City Utah. They can hook you up!!

So worth it! Now I have power like driving my car!!

duttch1 · 04-02-2023, 04:02 PM

Hey guys, thank you so much for the support and info! I spent most of the day on the Cummins and completely agree, all mechanical and Cruise control is the auto rev issue. It has a KC-2500 (CR 3102 or 8102) servo unit that is the throttle actuator for the cruise control. When I first turn the key on I heard a noise that sounded exactly like an electronic fuel pump. It turns out it is the KC-2500 servo unit chattering away.

I also replaced the Bosch fuel overflow valve as I saw there were a lot of posts about it. I put the Tork Teknology adjustable valve in (preset at 30psi) and there was no difference in power.

Oh and you are correct again, it has a throttle cable all the way to the pedal. The KC-2500 is only for the cruise.

I'm not worried about the cruise module at the moment, just want the engine to have power. Tomorrow I will test fuel pressure and if that is good, I'm going to take it to a professional mechanic.

Thanks again and I will update solved issues