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Old 08-06-2019, 01:44 AM   #1
Junior Member
jfrankiejones's Avatar
Brand: Thor Motor Coach
Model: Windsport
State: North Carolina
Posts: 2
THOR #1788
Onan generator woes!!

Try this again, first attempt at post failed.

I have a 2015 Windsport with a Onan 5500 that has not run good this summer.
For a while, it would run fine while stationary and after we hit the road it would shut down. Most of the time after we realized that it had, we could restart it with no problem.

After reading forums and watching YouTube, i replaced the fuel filter, fuel pump and air filter. Now it will run for about 30 mins and shut down after loping and black smoke out of exhaust. I'm having problems getting it restarted, usually have to wait a couple of hours or next day?

This evening I was gonna run it some and then spray in Sea Foam hoping to clean the carb. It ran for 37 mins and shut down, I removed the air filter and hit the start button and had a ball of fire come out of the carb. I waited about 15 mins and tried again and it started. I sprayed sea foam, let it run for 5 mins and shut it down for 10 mins. Tried to start it again and gas or sea form came out of the carb throat, but no fire.

I have run out of ideas of what to do, would appreciate any suggestions or information on what to do now?

Thanks in advance!

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Old 08-06-2019, 02:26 AM   #2
Senior Member
Calman's Avatar
Brand: Thor Motor Coach
Model: Vegas 24.1
State: North Carolina
Posts: 330
THOR #11380
Don't know where in NC you reside bu tmight want to find the nearest Cummins Diesel and have them check it out.

I live in New Bern and Coastal Diesel on US-70 East are great folks. Recently had them service the 4000 in my Vegas.
Cal Bridgers
YNCM USN-Retired (64-90)
RVN (Tet 68)
2015 Thor Vegas 24.1
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Old 08-06-2019, 12:53 PM   #3
Senior Member
Brand: Thor Motor Coach
Model: Hurricane 34J
State: Florida
Posts: 189
THOR #14384
When it stops running you need to pull the error code.

This video is about a onan diesel, but pulling the codes works the same.
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Old 08-06-2019, 01:11 PM   #4
Senior Member
Long & Winding road's Avatar
Brand: Thor Motor Coach
Model: 2017 Axis 25.4
State: Arkansas
Posts: 2,669
THOR #12231
That was great arp67. I would check for codes first.

How many hours do you have on your genset? Do you always use a fuel additive like Stabil when RV is in storage? Do you run the genset once a month to exercise it?

Sounds like carb trouble to me. If your adventurous like me I would remove the carb and clean + blow out with a compressor. Better yet ... see if they have a carb rebuld kit on line.

Also check fuel (again)?

Otherwise hopefully you will find the fault code that will lead you on to the correct path.

Might have to take to dealer but the way I see it is .... if its not working well.... try to fix it yourself then bring to dealer. You will be surpised on how much you can fix with the help of the internet and youtube.
2017 Axis / 25.4: Big Foot Levelers, Aims 1200 Watt inverter, Ceramic Window Tint, Full River AGM 6V batteries, Front Hellwig Sway bar / Rear Track Arm, Safe T Plus Steering Stabilizer, PD 4655 converter, Hard Wired Surge Guard, WEboost + WiFi Ranger, LED Headlights/Driving lights, TPMS, Surge tank, Tornado flush, Viair Compressor
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Old 08-06-2019, 01:33 PM   #5
Senior Member
The Gritz Carlton's Avatar
Brand: Thor Motor Coach
Model: THOR Chateua 35SF
State: Florida
Posts: 5,561
THOR #11130
Have you cleaned out the "spark arrestor" port?
Now an SOB
Traded Thor for Melbourne Prestige 24NP
2018 THOR Chateau 35SF
Two Labs, Bugsie & Blondie
Blondie passed in 2020 at 5 to Leukemia
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Old 08-06-2019, 02:09 PM   #6
Senior Member
Brand: Thor Motor Coach
Model: Windsport 34E
State: North Carolina
Posts: 303
THOR #13360
The black smoke sounds like a sticking float. That combined with the back fir I'd look at the float/float valve
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