Onan Generator Power Production Issue

[Globetrotter]

Hi,
Our 10K Onan starts/runs fine and was recently serviced with no issues noted on the unit itself. The issue below was occurring prior to having the genset serviced.
The issue as of late is that it produces power under a good load for about 20-30 minutes and then start tripping out. It will try to come back on and will only stay on if we run minimal load such as the fridge/tv. Anything more and it will cut out. The Genset itself remains running fine throughout.
On shore power all works fine and we can load it right up with multiple appliances/ac units etc.
If we leave it for some time and try again the same occurs, runs and produces good power for 20-30 mins and then starting shutting down the power supply or perhaps it is no longer producing the required power.
We do exercise the genset every month for a few hours under a good load. It worked fine all winter and started this issue on our way home.
I am thinking it is either the genset power production part of the genset or my power mgmt system in the rig.
Any thoughts or experience with this issue would be appreciated.
Thanks!!

[falconbrother]

Thanks for the update. In recent years, when I have some type of issue with whatever, house, car, RV, motorcycle, I dig into it myself. More times than not I have found that a big problem is caused by a small issue, like a wire that has come loose or grounded it's self.

[Globetrotter]

Here's the story in the hopes it may help others who may experience a similar issue.
I took it to a Cummins Service Centre who was very good at diagnosing and keeping me informed of their findings.
Here is the short version.
In taking apart the front access to the genset it was ultimately discovered that 2 wires related to the genset fuel pump had been pulled out of their connections. This due to the wiring harness being not being ideally secured and with some bouncing as we travelled over time they ultimately pulled right out of their connectors.
This made the control board try to compensate for inadequate fuel and ultimately it failed. Additionally an actuator was sticking and it was also replaced. Once both parts were replaced the unit ran well and produced power exactly to spec' during long tests. Problem solved however it was a pricey fix.
Check your wiring harness if you can to ensure you can avoid any wires being pulled out over time which could avoid a costly repair.
Safe travels!

[Globetrotter]

Taking it in to our RV guy this week and hopefully he can solve it. Thanks everyone!!

[bshpilot]

so the engine continues to run & NO breakers are trip....strange.

I wonder - is there a problem w/ the transfer switch ? is the voltage dropping too low to hold the transfer switch ?

[Globetrotter]

Hi everyone,
Thanks for your replies.
Firstly we do not run it when on shore power. I was just mentioning that when we do have shore power everything works fine indicating it is isolated to the genset.
The genset never quits throughout the issue. When the power stops breakers do not usually trip nor does the genset breaker trip although I have turned them all off and on to ensure none were partially tripped.
When the power ceases it simply goes out and then in a moment or 2 it starts to produce again and begins just as it does when the genset is 1st started.
I will test it again now that we have had all of our filters changed etc.. Stay tuned.

Thanks for your input!!

[bshpilot]

when it shuts down WHAT shuts down - the ENGINE stops or the breaker trips ?

There should be some CODE. Codes can be read by counting the flashes of the (on board) on/off/start switch/red light.

Heres the Manual (for my 10KQD), you'll need to confirm that yours is the same & if not search for the correct manual.

https://www.cumminsonan.com/www/pdf/manuals/981-0173.pdf

[cj7365]

Quick question, why would you run the genset when your on shore power??

[msturtz]

Please explain "cutting out" do you mean the generation stops running? Or does the generator breaker trip?

[cbr46]

There should be some codes from the gen shutting down.

There's another thread running with mysterious gen shutdowns. I seem to recall it pointing to a fuel shortage - enough fuel to run but not enough to run for extended time or under load. Check for blocked filters, cracked lines (air getting in).

Good luck,
- bob

[bullydogs1]

Check the gene connection in your transfer box..if something is loose and is causing resistance/heat...that would definitely make this behavior possible.