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Ductape's avatar
Ductape
Explorer
Jul 01, 2015

Onan gen stalls on rough roads?

This is a weird one. 5 kW model HGJAB, that's the carbureted one. Gasoline. Runs perfect in camp or on smooth roads. Occasionally stalls or (I think) stumbles only when on a rough road e.g. construction areas. Code 36 which is engine stopped without command from controller.

I say I think it stumbles at times without stopping completely because the UPS beeps as it does when the main transfer switch engages.

Always cranks right back up. Checked plug wires and air filter per manual. Nothing found. I am leaning toward either a carb float problem or a loose wire.

Theories? Thanks in advance for your advice.

Further info; 1 year in service and about 180 hours. Regularly exercised, fuel stabilized etc.

8 Replies

  • A soggy float is another thing to ponder. Centuries ago I used to weigh carb rebuild floats on a gram scale.
  • Still thinking floats but Could also be low oil cutoff. Even if levels are fine if the unit is off angle or oil is sloshing around (similar to gas in floats) it could be tripping the sensor.

    I know on my old portable Kipor even with proper oil levels all I had to do was tilt it slightly on its side and it would shut down.
  • Oil is good, thanks for suggesting. I don't have the manual in front of me right now but pretty sure the controller shows a code for that.

    Maybe some crud in the bowl that gets pulled up to block a passage and then falls back down? Seems too fancy a theory.

    Thanks for the spring idea Mex. sorta thinking out of spec on float level setting or some such.
  • I had a 47.5 HP Wisconsin do this on me and a stronger float counter-spring fixed the problem. Or you can remove the existing spring and pull it longer to make it stiffer.
  • Thanks, guys. I'm going to look up an Onan tech and see what they have to say. Seems to me that a genset for mobile applications should handle running over railroad crossings without stalling. None of my carbureted vehicles ever behaved this way; it's not hard to build a carb to handle jostling.

    I was hoping to hear from others either confirming the same experience or reporting that their genset runs reliably under such conditions.
  • N-Trouble wrote:
    Likely fuel is sloshing around in the floats not making to the carb. Don't think these things were designed to be banged around during use.


    This.

    And I don't think there is a "fix" either......except to not run the Gen while going down very rough roads.
  • Likely fuel is sloshing around in the floats not making to the carb. Don't think these things were designed to be banged around during use.

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