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Old 10-27-2021, 08:43 PM   #1
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Onan 4k issues

I have a new to me 2014 Winnie with a 4k Onan gas generator. The coach is in excellent condition, super clean and the generator only had 37 hours on it when I purchased it.
I changed the oil, air filter, spark plug and fuel filter.
It would never run more than 30-35 minutes then quit. While running it ran well and this was during the FL summer.
I started to do searches for the condition and found one solution that I thought had fixed it, particularly since I had just changed the oil. That was the oil overfill condition. So I drained a bit out to the point of the bottom of the add mark.
My next two trips were only an hour drive but the generator ran fine both ways.
I'm currently on a 2 stop trip.
On Sunday we traveled 4 hours and it quit about 2 and half hours into the trip. I got it restarted after 15-20 minutes and then it quit again in about 15 minutes.
Today we traveled less than an hour. It ran until just before our arrival. At the ranger station it started to surge and then quit.
This is so frustrating and become even more so once you start to search these conditions. It seems the possibility of fixes are endless. I read where one guy spent $4k at multiple shops until he got his genset figured out.
Anyone have any ideas on where to start on such a low hour genset. It will start fine and runs great then just quit and now the surging that started today. Thanks!
2015 Winnebago Vista 27N
St Augustine, FL
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Old 10-27-2021, 09:04 PM   #2
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Iím not an ONAN expert, but I have a little experience. I have had 6 toyhaulers in last 8 years. I bought all of them used and they each had the onan generator. I honestly believe your biggest issue is the 37 hours on a 2014 generator. These genies are made to run. That is not even enough hours for the at minimum 2-3 hours a month runtime with a load. On 3 of the 6 toyhaulers that had low hours I had to replace the carbureter and the fuel pump on the genie. Fuel sitting in the carb and fuel pump can setup hard deposits that cause issues like you are having. These ONAN generator carbs are not cleanable only replaceable. Iíve tried seafoam and other system cleaners but each time I had to replace the carb and fuel pump, not using these generators causes more harm than good. Hope this is helpful. I would start with the generator fuel pump
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Old 10-27-2021, 09:27 PM   #3
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I would suspect pinhole leaks in the rubber fuel line
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Old 10-27-2021, 09:30 PM   #4
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You can check my other lenghty post on onan gens.. 3 things..
1st use all safety precautions.. try to run fuel line pick up from 5 gal gas can..
2nd take air filter off and use carb cleaner.. spray into bottom of the carb throat.. there is a hole there.. called main jet.. don't lose nozzle and try to force cleaner pointed down into that hole.. spray the 1 or 2 holes in top part of throat.. let sit 30mins.. then where the fuel line goes into the bowl.. you have to remove fuel line and if it has a filter remove that and really spray there inside the inlet to carb.. let sit 30mins.. then try.. you can do both of these at same time..
3rd try to adjust the main jet.. that is the screw on bottom of the carb.. sometimes there is a altitude adjustment.. a black knob.. try that.. if still not smooth.. then pull knob off and try to adjust..

In step 1.. you rule out bad pump and fuel feed..

In step 2... you do a quick clean of carb..

In step 3... you adjust main jet.. to try and get trash out of main jet.. note keep close track of turns you use.. you may have to return back to original setting after fresh fuel gets in... 6 to 10 hrs of use

One other note are your slip rings clean and shiny?

Look up my other post.. and there are more ideas

You will find that onan carbs.. are easy to clean.. and out last almost every thing on rv..
Good luck and let us know what you did and maybe better members then me will help you
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Old 10-27-2021, 10:09 PM   #5
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I just thought of something else I wanted to add that could be of help in the diagnosis.
While pumping gas on Sunday and today have I NOT heard a intermittent rapid tapping or clicking sound from the generator. I have heard it all other times except this trip.
2015 Winnebago Vista 27N
St Augustine, FL
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Old 10-30-2021, 06:20 PM   #6
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The generator ran fine today for 3 hours of our journey home. From the time we started it until I shut it down in the driveway it did fine. I was hearing the rapid intermittent tapping/clicking, however, in the driveway.
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