Hi all,2002 Holiday Rambler with 7500 Onan gen. Ran gen 12 hours yesterday ran just fine. Now when I start it up it runs for maybe 30 seconds then stops. 1. Diesel tank is full2. Changed out air filter it was pretty dirty. 3. Checked oil and coolant levels- goodPrimed it according to manual for 1 min same results.Primed it for 5 min same results. Could it not be getting fuel, should I change out fuel filter also.Bit of history. Our first RV, bought a repo cause that's what we could afford. The previous owner definitely did not take care of it nor did he do maintenance. Took us 2 days to get it 150 miles home. Changed fuel filters multiple times, new air filter cleaned fuel tank had algae and water in tank. Cummins runs great now we just came back from Disney over the holidays with the little ones. I do all the work on it so I am learning as I go. Any help is appreciated. Kit

Yes, change the fuel filter(s). Always do the simple things first. Even if it's not the problem, you will know when it was changed for future maintenance.

Ok great will do that. But let's say that doesn't do the trick what should I look at next?

Did you check for any rubber fuel lines that may have collapsed?It sounds like your rig didn't get the best maintenance from the PO.Check all the lines.

Locate the oil pressure sensor if equipped. Defective oil pressure switch shuts it down so no damage occurs(if you are lucky). A defective switch or clogged opening will cause shutdown.

Oki doki, tomorrow I will replace fuel filter and check the 2 fuel lines. Any idea where the oil pressure senor switch might be located and what's it look like? I have the original manual but it's not too much help. I have checked the fault codes when it shuts down. Same as my previous post, I have bought replacement ceiling lights with better manuals.

7500 Onan Gen won't stay running. | Good Sam Community

Kitcarsen
Explorer
Apr 19, 2017
All,
Thanks for the advice. I finally got to it several weeks ago. I did check fuel lines but I never changed the fuel filter. Bingo!! $8 later generator up and running.
RCL
Explorer
Jan 15, 2017
one thing to check is the fuel line to the generator. I was getting a code 36 and did all the usual things, fuel and air filters, to no avail. My gen set is on a slide, and the fuel line was cracked and leaking. That flexing on gen in and out caused it to crack. When the gen set was sucking on that line, it pulled air in and the gen set would lose prime and quit. Replacing that line fixed the problem.

Dick L. '04 HR Imperial
ro_sie
Explorer
Jan 09, 2017
Kitcarsen, I know nothing about generators. I want to thank you for your service. If we were closer I would offer help to your wife while you are serving our country. I thank her for her service also. We were a former military family also, during nam. Again, thanks to both of you. It is greatly appreciated.
Kitcarsen
Explorer
Jan 09, 2017
Ok well nothing open on a Sunday for me to get a new fuel filter. Lesson learned for a new RVer keep filters, oil, etc on hand. Have to take off for few months gonna have to work it out when I return from deployment. Wife is handy maybe I can get her to swap it and look for fuel leaks where air might get in the system. I will post my findings after this deployment. I think the air in the system is a good guess. I had an air issue with the fuel filter on the Cummins when we bought it few months ago

Kit
De Oppresso Liber
Matt_Colie
Explorer II
Jan 09, 2017
Kit,

I have lots of diesel experience, and what you have sounds very much like a "low side leak". That means that part of the fuel system where the fuel is being drawn in has a leak that lets air in. This is why bleeding is a temporary fix. These things are a bear to find, but look for anyplace that has external evidence of fuel that should be dry.

I have most often found these leaks in the base gasket of screw on fuel filters. It does not take much and a crease or wrinkle will do it. Get your cloves out, you will end up with fuel on your hands....

Good Luck

Matt
Big_Katuna
Explorer II
Jan 08, 2017
Make sure oil and water are topped off.
mikestock
Explorer
Jan 08, 2017
This or this should give you some answers.
Tom_Barb
Explorer
Jan 08, 2017
Kitcarsen wrote:
Great thanks for the info. Gotta do it tomorrow. Make sure it's ready for family while I am gone for next few months. We lose power here often during the winter. I will follow up to see if these things get it running.

Question: are the fault codes all standard for Cummins gens? I get either 26 and/or 36.

Kit
De Oppresso Liber

I believe so..codes by the number
Kitcarsen
Explorer
Jan 08, 2017
Great thanks for the info. Gotta do it tomorrow. Make sure it's ready for family while I am gone for next few months. We lose power here often during the winter. I will follow up to see if these things get it running.

Question: are the fault codes all standard for Cummins gens? I get either 26 and/or 36.

Kit
De Oppresso Liber
enblethen
Nomad
Jan 08, 2017
I believe the switch is just above the oil filter.

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7500 Onan Gen won't stay running.

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