I’m thinking I know the answer but still have to look at the owners manual. Just got back from our first trip. Cummins Onan 5500 gas generator. The trip there was no problem. Generator ran fine the entire 7 hours it was on. On the way home it shut off 2 hours into the trip, I noticed when it started to get warm inside. Started it back up and it took a couple times but it started. Ran for about 45 minutes then died again. It was 90 degrees on the way home. The trip there wasn’t as warm and it rained for the first 2 hours. I’m thinking it got hot and shut down. When I got home I checked the oil level and it was full. I ran it for 2 hours in the driveway and it ran fine. So a couple thing I think it could be. it got hot and shut down to protect itself. The fuel was boiling due to the heat. Or what I actually did find was the altitude setting was at zero feet. We are around 900 feet where we live. Is it possible being at zero in high temps would cause it to shut down? I know it’s a long shot but it’s the only thing I found.Im still leaning towards vapor lock.Thanks!

Overheat shutdown is a common problem. It should have thrown a code on the panel when it happened. Used to happen on a model we had years ago. Poor design by the manufacturer put the genset bin right behind the engine headers so it picked up a lot of extra heat. Installed some louvered vents in the bin door and that helped keep airflow over it and it never happened again. We ended up selling that RV and in shopping for any new one, genset placement is a consideration.

I'd go with the genset overheated and shutdown as a result, as the explanation. And, if there's any part of the fuel line that is metal, it may have created an air bubble in the line and consequently a vapor lock.900ft elevation is not really all that much when considering air/fuel mixture. In aviation, small-plane pilots will start to lean out the mixture when they get up around 2K-3K feet to compensate for the thinner air. If 900ft elevation actually did affect the mixture, the genset would likely have run a little rich and maybe smoked some, but I doubt it would have shut down, and if it's running rich, the extra fuel would cause a cooling effect on the engine.

That’s what I’m thinking too, overheat. But I don’t have a panel that would show codes, just an on/off switch behind the cover. What would show codes?

dodge guy wrote:That’s what I’m thinking too, overheat. But I don’t have a panel that would show codes, just an on/off switch behind the cover. What would show codes?The small screen that shows the gen hours is where the code would be. you should have a remote switch in the RV on your panel with all your other controls. That said, it's a moot point now as the code only shows when the issue is actually happening.

dodge guy wrote:I’m thinking I know the answer but still have to look at the owners manual. Just got back from our first trip. Cummins Onan 5500 gas generator. The trip there was no problem. Generator ran fine the entire 7 hours it was on. On the way home it shut off 2 hours into the trip, I noticed when it started to get warm inside. Started it back up and it took a couple times but it started. Ran for about 45 minutes then died again. It was 90 degrees on the way home. The trip there wasn’t as warm and it rained for the first 2 hours. I’m thinking it got hot and shut down. When I got home I checked the oil level and it was full. I ran it for 2 hours in the driveway and it ran fine. So a couple thing I think it could be. it got hot and shut down to protect itself. The fuel was boiling due to the heat. Or what I actually did find was the altitude setting was at zero feet. We are around 900 feet where we live. Is it possible being at zero in high temps would cause it to shut down? I know it’s a long shot but it’s the only thing I found.Im still leaning towards vapor lock.Thanks!As long as it'clean with the intake air and such, I'd be looking for an oil overtemp switch. I finally disconnected ours on our old Generac and ran it that way for years.

Generator question | Good Sam Community

24 Replies

way2roll
Trailblazer
Jul 02, 2019
dodge guy wrote:
That’s what I’m thinking too, overheat. But I don’t have a panel that would show codes, just an on/off switch behind the cover. What would show codes?

The small screen that shows the gen hours is where the code would be. you should have a remote switch in the RV on your panel with all your other controls. That said, it's a moot point now as the code only shows when the issue is actually happening.
dodge_guy
Explorer II
Jul 02, 2019
That’s what I’m thinking too, overheat. But I don’t have a panel that would show codes, just an on/off switch behind the cover. What would show codes?
10forty2
Explorer
Jul 02, 2019
I'd go with the genset overheated and shutdown as a result, as the explanation. And, if there's any part of the fuel line that is metal, it may have created an air bubble in the line and consequently a vapor lock.

900ft elevation is not really all that much when considering air/fuel mixture. In aviation, small-plane pilots will start to lean out the mixture when they get up around 2K-3K feet to compensate for the thinner air. If 900ft elevation actually did affect the mixture, the genset would likely have run a little rich and maybe smoked some, but I doubt it would have shut down, and if it's running rich, the extra fuel would cause a cooling effect on the engine.
way2roll
Trailblazer
Jul 02, 2019
Overheat shutdown is a common problem. It should have thrown a code on the panel when it happened. Used to happen on a model we had years ago. Poor design by the manufacturer put the genset bin right behind the engine headers so it picked up a lot of extra heat. Installed some louvered vents in the bin door and that helped keep airflow over it and it never happened again. We ended up selling that RV and in shopping for any new one, genset placement is a consideration.

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