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Old 06-23-2019, 02:19 PM   #1
Junior Member
Join Date: Aug 2017
Location: Orlando, FL
Posts: 4
Onan Generator Engine problem

I have a 2016 Prime time Spartan Toy Hauler with a built in Cummins Onan RVQG 5500 EVAP generator. The generator works fine. The problem is the generator engine surges (speeds up & down on its on) when there is no load. I have always used non ethanol gas in the engine. I have taken it to an RV shop and they removed and dissembled and cleaned the carb. This did not help. They have adjusted as well as my self the air mixture screw, no results. The shop wanted to replace the carb with no warranty that it would fix the problem. I said no thanks.I have replaced the fuel pump (other one stopped pumping), fuel filter, air filter, plugs, oil and this did not help. Under load the engine maintains a fairly steady speed. Its not perfect, but I can live with that. Has anyone else had these problems and if so did you fix hem? If so what did you do to correct the problem. Thanks for the help.

Reg3691489 is offline   Reply With Quote
Old 06-26-2019, 08:46 PM   #2
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Join Date: May 2017
Posts: 9
I also have a Spartan '17 and have a very similar problem with my gen. Mine has an issue where it will over-rev when all load is removed and it shuts down. I took it to Cummins and they couldn't make it fail but indicated that its probably the carb. I haven't replaced it yet but I will at some point.

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Old 06-26-2019, 08:53 PM   #3
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Join Date: Jun 2015
Location: payson, az
Posts: 2,207
take it to onan! they have a 2 year full warranty and a 3 year warranty on major components. a 2018 should still fall within the 2 year warranty period.
2015 cardinal model 3825fl
2015 dodge ram 3500 dually
CHICKDOE is offline   Reply With Quote
Old 06-26-2019, 09:22 PM   #4
Join Date: Apr 2019
Posts: 54
take off air filter.
start gen
place hand over air intake to restrict air flow which will enrich fuel mixture.
When idling you may have to restrict incoming air quite a bit.
If engine stops hunting, then you know the mixture is too lean and its a carb issue.

Otherwise it is the governor is setup wrong, wrong spring position maybe.
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Old 07-15-2019, 10:24 AM   #5
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Join Date: Aug 2013
Posts: 10
Onan issues

I also have issues with mt Onan. I did a work around on the no load surge problem by turning the choke to close part way until the surge stops at not load The carb is defiantly too lean. altitude is set to 0.

Now the thing keeps shutting down when the load clicks off due to over freq. code 14. I have the gov spring so loose it barly runs at 110 volts under load and wont power both AC units.
I have been all thought the thing and I am at a loss as to what to do next.
RapidRoy is offline   Reply With Quote

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