ONAN MAJB Generator wont stay running.


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kurtwt

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I have an ONAN MAJB Generator that will run for a while say, 20 min and then start going down in Rpms and either die or resume normal RPM. Mostly it will just die. I checked the water pump and it is fine. Anyone have any ideas, i have ordered a new spark plug. If i need to pull it out to work on it, do i have to pull one of the main engines to do that. I just rebuilt my port engine and will be doing the starboard next. But i would like to pull the gen set and get it working for the rest of the season.
 
i have several dock mates with those older Onans, IMO they seem to be pretty problematic. one guy buys points several sets at a time and when it quits running, he throws a new set on it. he does this about once every three or four months. can you determine if you are having a fuel issue or firing issue?
 
kurtwt said:
I have an ONAN MAJB Generator that will run for a while say, 20 min and then start going down in Rpms and either die or resume normal RPM. Mostly it will just die. I checked the water pump and it is fine. Anyone have any ideas, i have ordered a new spark plug. If i need to pull it out to work on it, do i have to pull one of the main engines to do that. I just rebuilt my port engine and will be doing the starboard next. But i would like to pull the gen set and get it working for the rest of the season.
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Have the carbs cleaned out really well, replace the fuel filters. Some bad gas may have reduced the flow. Happened to me on my Kohler.
 
Currently dealing with a no spark issue myself. Found some good info on smokstak.com There are three sensors that cause a shut down. Low oil, high engine temp, and high exhaust temp. I would guess you are dealing with the high temp issues. Check impeller and cooling system flow. I have the original manuals in front of me now.
 
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