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havin problems with my generator!!

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2007 Rage'n fsc2800, it has a onan 5500 marq. gen. Just coming up on 200 hours. The first trip of the season (trip before last) the problem started. Gen. would run which seemed about as long as it took to warm up 15-30 min and it would almost act like it was vapor locking or running out of gas. Let it sit for a hour and it did the same thing again. The gas in there had been sitting for about 4 months with stabalizer in it so I thought maybe it was bad gas. When I came home from that trip I drained the tank and filled it up with fresh gas on this last trip out hoping that was the problem.

Got to our destination for the turkeyday trip, didn't really run the gen. during the day only to toast bread or microwave something. My lady ran the gen. at night to watch a movie before bed (2 hours or more) and it ran flawless. So, I figured it was the gas and i was in the clear! It ran about the same the next day only used it for a couple min during the day and ran fine at night for a movie again. But then the next day I had a buddy that needed to charge his batteries so I plugged him into mine and ran the generator, about a hour into it it started to spudder and stall out again. So, I killed it and let it sit cause now I know there's something wrong and only used it if it was needed ie; toaster, or microwave for a couple min at a time.

So here I am now hoping for advice. Vapor lock, Gummed up carb?, fuel pump going out????? any help would be great!!!! thanks....... :lol:

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Did you look at the genny to see if there was a code showing? On my 4.0 there is an indicator light that will flash a simple prob code. The carbs aren't that great so it may be the problem. I think those carbs are sealed so the only thing to do is replace it. You might want top try an inline fuel filter since I have seen some rust discoloration in my tank. You might also check your oil. I think at 200 hours you are due for a change and maybe if the oil is dirty it is messing with the low oil sensor.

One of my co-workers is having a similar problem with his 4.0. Good luck.

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I just did the oil at 150 hours, so, unless the guy gave me the wrong weight oil at the rv place I got it from?? It's not low on oil, but I did read about that low pressure switch.

If it was a carb or fuel pump issue it should do it no matter what, right? Not just when it gets Hot?

But the last time it did it I popped the front cover off and the internals were too hot to touch, not sure if that's normal since these are just air/oil cooled. But it did backfire when I tried to start it one time. Maybe there is a clogged/gummed up jet or something that's leaning it out and causing it to run hot? I dunno, I'm gonna give a few mechanics I know a call and get their take on it before I burn the thing up trying to figure it out.

Thanks for the reply, any other idea's are welcome, or if anyones ran into the same problem.

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Qualifications: head of 4stroke service at Sierra saw. 10 years in the industry.

Although I do not have a ton of experiance with the onan brand this problem is common. Since your fuel did sit for a while i would head towards a deteriation of a fuel system component. could be a bead of water floating the the carb bowl. The fuel pumps on these engines usually either work or dont work. You could have a vapor lock condition. Check your alcohol level in your fuel. also make sure your gas cap is venting properly.

it does not sound like an ignition issues. The low oil shut downs will kick on imediatly if the oil is low.

Feel free to contact me if you need any additional help

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@zuch, thank you for the reply! I drained all the old gas out of the tank before the last trip and put fresh pump gas in and as I said it ran fine all night watching a movie for 2 nights, but during the heat of the day is when its done it, never at night. My dad and I both think vapor lock, or def. something carb. but if its vapor lock why now? I've had the rig for 4 years and this is the first time it's ever done anything like this. Been in 90+ degrees with the ac lugging for hours and ran fine...

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@zuch, thank you for the reply! I drained all the old gas out of the tank before the last trip and put fresh pump gas in and as I said it ran fine all night watching a movie for 2 nights, but during the heat of the day is when its done it, never at night. My dad and I both think vapor lock, or def. something carb. but if its vapor lock why now? I've had the rig for 4 years and this is the first time it's ever done anything like this. Been in 90+ degrees with the ac lugging for hours and ran fine...

Usually vapor lock is very rare. It could be related to a high alcohol fuel, that would be the only thing that usually causes it. You could check for a fuel line close to a heat source. The fuel may be boiling in the fuel line. I have seen this happen on some riding mowers in the summer.

In california we have tons of issues with E25 and E85 fuel getting into units. Anything over 10% will give you all sorts of issues.

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Here in Cali, we have had some issues with ARCO fuel in air-cooled units, as it appears that the alcohol content is rather high.

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the fresh gas that is in there was from a 76 station. thank you for all your replies, i'm gonna start to tinker with it this weekend. hopefully I find something to put me on the track of resolving the issue.

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the fresh gas that is in there was from a 76 station. thank you for all your replies, i'm gonna start to tinker with it this weekend. hopefully I find something to put me on the track of resolving the issue.

I would start with the fuel line, check for cracks or it close to the engine etc. Good luck.

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my onan gave me intermitent fits..fuel pump was pumping....finally just replaced the pump and its been great ever since. Replaced the filter too.

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