7500 Onan Gen won't stay running.

[Kitcarsen]

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 full
2. Changed out air filter it was pretty dirty.
3. Checked oil and coolant levels- good

Primed 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

[Kitcarsen]

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]

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]

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]

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]

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]

Make sure oil and water are topped off.

[mikestock]

This or this should give you some answers.

[Tom_Barb]

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]

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]

I believe the switch is just above the oil filter.

[Tom_Barb]

Run the fault code test..
Fault Codes
The genset controller provides extensive diagnostics by causing the status indicator light on the Control Switch to blink in a coded fashion. Following a fault shutdown, the indicator light will repeatedly blink one, two, three or four blinks at a time.
• One blink indicates shutdown due to high engine coolant temperature.
• Two blinks indicates a low oil pressure fault.
• Three blinks indicates a service fault. Press Stop once to cause the
two-digit, second-level fault code to blink. (Pressing Stop again will stop the blinking.)The two-digit code consists of 1, 2, 3, 4 or 5 blinks, a brief pause, and then 1 to 9 blinks. The rst set of blinks represents the tens digit and the second set of blinks the units digit of the fault code number. For example, Fault Code No. 36 appears as: blink-blink-blink—pause—blink-blink-blink-blink-blink-blink— long pause— repeat
• Four blinks indicates that cranking exceeded 30 seconds without the engine starting.
Note: Fault Code Nos. 3 and 4 are rst level faults. Avoid interpreting them as second-level Fault Code Nos. 33 and 44, which have not been assigned as fault codes.

[Tom_Barb]

trouble shooting manual

[Kitcarsen]

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.

[enblethen]

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.