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Dastagg's avatar
Dastagg
Explorer
Jun 17, 2013

More Generator Issues?

I just spent around $1,500 getting my generator (Onan 4000) to get it to run. Had plugged carburator thanks to Ethanol in fuel, voltage regulator and other small items. It now runs great and starts great, however,I sent camping this past weekend and started my generator to cool Motorhome about two hours prior to leaving and upon trip about the 2nd hour of trip, the generator died on the way. I tried to restart with no luck. It would crank but die just after letting go of the starter switch. Finished the travel and after a few hours, started the generator and seemed to run.

Did my camping for the weekend and ran generator all the way home of about 2 hour trip and ran entire trip and while home, I ran it another two hours without it shutting down. The first time, it ran close to 3 - 4 hours before it shut down. Now am wondering if the first time was a fluke or more to come later. I checked and it has full oil level and fuel tank was full or close to full when it died and never fueled up on trip either, so it ran on same fuel level coming home as on trip to camp spot. Just not sure what to think about direction I need to go.
Class C
  • Dastagg's avatar
    Dastagg
    Explorer
    Jun 18, 2013
    Thanks and will look for the code. I did find on another internet site that this same issue is a very common issue with Thor Motorhomes. Thor knows of the issue and is an issue of heat possibly vaporizing the fuel going to the generator. Seems that the heat from engine and roadway is overheating the fuel causing the vaporization which is possibly why after running for a couple of hours, it was not problem and I tried to simulate issue on driveway to never shut down on me. Am told that it is generally while traveling while running generator in the good old Texas heat which we had 99 degree temps this past Friday. Will have to see next time if it does again and look up code but Thor is not doing a lot to correct the issue and either way, mine is a 98 model which they likely wouldn't really care anyway but seems to be an issue with newer versions also.

    Maybe no one else has seen evidence of this same issue? Where I saw it was on another Forum and had quite a few had similar issues while driving down the road in 95+ temperatures.
  • rbutton's avatar
    rbutton
    Explorer
    Jun 18, 2013
    if you don't have them here is a link to the PDf files for the Service Manual and Operators Manual for the Onan 4000. The operators manual shows the codes and how to check for them. It would be interesting to see if it's displaying any codes.
  • Dastagg's avatar
    Dastagg
    Explorer
    Jun 18, 2013
    Thanks or all the help. Great idea on fuel pump switch. Still can't imagine what would cause the gen set to shut off after several hours but will look at the fuel hose as suggested also. Should not get any hotter after an hour or so compared to a few hours, but who knows?
  • Dusty_R's avatar
    Dusty_R
    Explorer
    Jun 18, 2013
    2oldman wrote:
    Dastagg wrote:
    plugged carburator thanks to Ethanol in fuel
    Not sure about that, but if you get it running good, find a way to drain the fuel for storage.


    The fuel pump is electric. I added a switch just ahead of the fuel pump, turn the switch off when done with generator, and let it run out of gas.

    Dusty
  • mfox20's avatar
    mfox20
    Explorer
    Jun 17, 2013
    How old is the motorhome and generator? This is a classic symptom of a failing fuel line from the main tank. I had the same issue on a 10 year old coach with an Onan 5500 here in Fort Worth. And older fuel line will develop small cracks and suck air (sometimes).

    Mine would run great in cooler weather but had the same symptoms in the high heat. Thought it might be vapor locking but after replacing the entire line from the main tank to the generator fuel pump it has never died again. Need to also look at the line from the fuel pump to the carb.

    Hope this helps.

    Michael
  • Sandia_Man's avatar
    Sandia_Man
    Explorer II
    Jun 17, 2013
    I would run it some more and see if you can get it to reoccur. I have the same Onan genny and just use the cheapest gas available that always has ethanol in it and never had a problem, but I use Stabil along with an occasional bottle of Seafoam. Over 700 hours over the last 6 years and it runs like a champ, even purchased a fuel filter years ago but have never had cause to replace it as of yet. Here's hoping you get it figured out as my DW can not do without our genny.
  • Bobbo's avatar
    Bobbo
    Explorer II
    Jun 17, 2013
    I was going to suggest an oil level that was borderline low, but you covered that in the first post. I have seen borderline oil levels kill a generator in a hard curve or steep hill.
  • dan-nickie's avatar
    dan-nickie
    Explorer
    Jun 17, 2013
    Dastagg wrote:
    As stated, I was full of fuel, oil, and spark plug changed just last month. Not sure about codes as I am not aware of how to read codes? I suppose I will call the mechanic also, however, as states above, it needs to be able to be reproduced to diagnose issue and not sure it if was a one time deal or just didn't reach that point again yesterday and didn't shut down. Shut down about 3 - 4 hours the first time and yesterday it ran 5 hours before I shut it down waiting on it to shut itself down.


    Alrighty then. I guess the spark plug was included in your 'other small items' :)
  • Dastagg's avatar
    Dastagg
    Explorer
    Jun 17, 2013
    As stated, I was full of fuel, oil, and spark plug changed just last month. Not sure about codes as I am not aware of how to read codes? I suppose I will call the mechanic also, however, as states above, it needs to be able to be reproduced to diagnose issue and not sure it if was a one time deal or just didn't reach that point again yesterday and didn't shut down. Shut down about 3 - 4 hours the first time and yesterday it ran 5 hours before I shut it down waiting on it to shut itself down.
  • j-d's avatar
    j-d
    Explorer II
    Jun 17, 2013
    Did you run your fuel tank low, the time it quit?

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