1996 Cummins C8.3 300 Shut Down No Re-Start

[JESTIMATOR2]

So other morning we were getting ready for a short trip to go see my son for his 21st birthday and I did my usual checks and fired up the engine and let it idle, build air pressure, etc. It sounded great as usual. After about 20 min of running as I was walking around to disconnect the shore power I heard the engine sputter like it was running out of fuel then it picked back up again and smoothed out, 30 seconds later it did it again and shut down. I tried to re-start and nothing. Fuel gauge showed a little over 1/4 tank. Thinking the gauge might be bad I tried the generator and it ran fine for about 10 min and then I shut it off.

So I figured the tank is low and I picked up some junk, so I drained the water separator, no water just fuel. Tried to start again and nothing. Off to Napa to get new filters, RV is new to me so I had no idea when the PO last changed them. Changed both filters, cracked the line between the second filter and injection pump, manually pumped it til fuel came through steady. Tightened line down and had the wife try it and it fired up and idled, she rev'd it a bit then let idle and after a min it shut down again, no re-start. So I figured has to be the fuel transfer pump...so off to O'reilly and back with the new pump. I get it installed, prime everything and try to start...nothing. I prime it again and then this time depress the fuel pedal about half way after 10 sec it starts to sputter like it wants to start. I give starter a rest and try again and she fires up and runs smooth (as long as we keep our foot in the pedal) if you try to let it idle it wants to stall, get back in the pedal and it smooths out again, let off the pedal all together and it shuts back down...no re-start.

So now I am wondering about the fuel gauge again...my son in law gets under the coach taps on the tank and it sounds pretty empty...so off I go to get 10 gal of fuel to put in it...get it fueled, gauge moves up, then go back to prime again...but when I crack the line this time fuel is flowing steady. So tank must be good right? So I pump it up a few times for good measure and try to re-start...nothing!

This was last night at 8:30 and in order to keep peace with my neighbors and save my starter I figured it was time to stop.

I am truly at a loss here...it ran beautiful...then this. I'm sure if I get it started again as long as I stay in the pedal it runs...anyone have any thoughts on this?

Sorry about the long post....I wanted to be as detailed as possible in case this happens to someone else in the future on one of these old mechanical motors (which I still love by the way!)

Thanks!

[Skip426]

I believe your year of mechanical Cummins engine has the P7100 injection pump; and you may have a failing '" fuel shut off solenoid".

The solenoid is a lift and lock mechanism and has two fuses , one for each circuit.
Here are some diagrams and a wiring schematic.
The fuel shut of solenoid can be operated manually , by attaching a wire to the pivot arm of the pump to hold the arm in the run position.
Remember you have to be able to access the wire to shut the engine off if it starts.

[Reodad]

I apologize for not being able to offer any helpful advice to remedy your problem as I am still a novice at owning a MH and at dealing with diesels. But i have a question. I have a rig with a Cummins 350 isc (2003). From what I have learned you should not allow your diesel to sit and idle for over ten minutes. 3-5 minutes on cold start up is optimal (depending on build up of air pressure, oil pressure, temperature on engine and tranny, etc). 3-5 minutes is also a must for cool down once reaching the destination. Don't remember all the particulars why, but it is supposed to be harmful to the engine to not allow these times of warm up & cool down. From your post and one or two others I have read recently it seems some folks can let their rigs idle for up to a half hour and beyond. Am I missing something, do I have my operating procedures wrong? Is it possible the long idle had something to do with a shut down? Still learning and just asking!

[JESTIMATOR2]

Thank you Skip426! The valve is operating however it is being held in with a zip tie and moves vertically every time it operates! The PO told me it came loose one day and he could not shut the engine down. I purchased the proper bolts and I am going to secure it properly. It is possible it may not be opening all the way. I will check it out....thanks for the schematics!

[JESTIMATOR2]

Reodad...I started off in the construction industry driving an old Mack dump truck...my boss then insisted we never let the engine idle more than a couple minutes...he said it caused build up in the engine that was harmful....those old trucks had a a pull lever much like a choke pull that you could pull out and increase the idle speed and lock it. That being said, I am usually ready to roll in my rig shortly after the air tank pops off so I usually am not idling too long....I try to avoid it if at all possible since it was ingrained in my head to be a bad thing from a young age! However, I doubt the idling had anything to do with this issue though.

[deandec]

x2 on the fuel shutdown solenoid.

It sounds like the "Run" magnet is not being maintained with the wire tie (too loose) but the "Start" magnet is strong enough to pull up the rod to the start fuel position.

installing the tie down bolts should work if the PO did not change the usable height of that shutdown rod.

Replacement solenoids, if needed, are on EBAY for $30 or Cummins will sell you one for $370 plus labor.

I just installed one recently.

[MichaelU295]

JESTIMATOR2, hope that you got your rv up and running again. Please share your result.

Thanks,
Michael

[JESTIMATOR2]

Update! Ok folks I got the fuel shut off solenoid bolted up proper, PO had broke one of the screws, could not extract it so I put the remaing two in with loctite (blue) and she’s in good...no more zip tie! Bad news, got it started and it stalled out again after 5min. To rule things out I met one of my foreman at a shell and put 66 gal fuel in his transfer tank and we pumped it into the RV. I went and primed the low side and then tried it...AND IT RAN AND RAN AND RAN AND IT STILL RUNS!
So long and short my fuel gauge is wrong or my fuel pick up tube is broke (rotted) off above the 1/4 tank mark. I’ll finish determining this when I get it to the gas station and top it off. I put a total of 75 gal in, if it takes another 75 I have a gauge issue, if it doesn’t, I have a fuel pick up tube issue. I will keep you all posted. For now she is purring like a Cummins and I am happy! Thank you all for your help and well wishes! By the way...it runs much better now with the new filters and pump and solenoid bolted in correctly, so I am not sorry I did any of those repairs!

[JESTIMATOR2]

@deandec thanks for the tip on the solenoid, checked it out and they are available and much cheaper! Thank you!

[Andy M]

From my 11 years of experience with my Motorhome and motor homes in general, you are seriously playing with fire if you have anything less then about 35 gallons in the tank. Do not let it get below 3/8th, and that is very risky as well. They are unlike a car or truck.

[twinboat]

Your fuel pickups may be crossed. Typically the generator uses a shorter pickup tube. They do that so it doesn't leave you out of fuel in the middle of nowhere.

[JESTIMATOR2]

@Andy M trust me she wont let me get below 1/2 tank ever again[emoji6]

@Twinboats I thought the very same thing as well could have been a mistake at the factory or during a previous repair. No simple. If it does not tank 75 gal when I go to fill up that will definitely be one of my checks...especially since the generator was still running and engine would not.

[Bob_C]

Love it when an M/H owner can work on his rig.......

[RKins]

You didn't say (unless I missed it) if the fuel gauge went up with filling it with the 66 gals - or what size tank you have. You mention another 75 gals so I assume 150 gals?