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427435's avatar
427435
Explorer
Jun 17, 2016

Onan genset stops running--------Fixed

Finally got the MH out. The genset started up OK and I let it run while I did some other things with the MH. It started to surge after 10-15 minutes and quit. It restarted after setting for a while. That cycle continued several times this afternoon.

My best guess is a mouse nest causing the overheat temp sensor to kick out. I won't have time to deal with it for a couple of weeks, but I'm interested in other possibilities to check before I pull the shrouds (which looks like it requires pulling the genset out). :(
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  • mcal63775's avatar
    mcal63775
    Explorer
    Jun 17, 2016
    My Onan 7000 Marqui experienced same problem. AFTER a new fuel pump and fuel filter (carb was replaced a year prior to this problem), it STILL continued. I ran a new gas line to fuel pump and from a gas can....it ran great. Found a split gas line from fuel tank to fuel pump. Replaced the line. Problem resolved.
  • johntank's avatar
    johntank
    Explorer
    Jun 17, 2016
    427435 wrote:
    Finally got the MH out. The genset started up OK and I let it run while I did some other things with the MH. It started to surge after 10-15 minutes and quit. It restarted after setting for a while. That cycle continued several times this afternoon.

    My best guess is a mouse nest causing the overheat temp sensor to kick out. I won't have time to deal with it for a couple of weeks, but I'm interested in other possibilities to check before I pull the shrouds (which looks like it requires pulling the genset out). :(


    I just had a similar problem with my Onan 4000 in my 5er fuel pump and filter new last year so had good fuel flow, a Cummins shop in my area after checking it out said it was a bad carb.

    PM me if you want more info.
    John
  • soxbrat's avatar
    soxbrat
    Explorer
    Jun 17, 2016
    I'm having a similar problem in a 5th wheel toy hauler. I've replaced everything,i.e., spark plugs, filters, etc., except the fuel pump. I've been trying to find out what the amp draw should be for the pump so that I can check it out.I'll be interested to see what your final analysis is. If I get this problem corrected I'll post.
  • mikestock's avatar
    mikestock
    Explorer
    Jun 17, 2016
    Surely sounds like a possible fuel line or filter problem. I found that Tiffin, for some reason, places a small fuel filter ahead of the Onan, built in, filter. Cummins said to take it out and replace it with a hose splicer. I did so and my problems ended.

    I don't, personally, know if Tiffin is the only builder to add this useless filter.
  • sdianel_-acct_c's avatar
    sdianel_-acct_c
    Explorer
    Jun 17, 2016
    The generator has codes if you can get a copy of them. Ours did the same thing and we took it to Cummins. The tech tried the switch and said "fuel line getting air".... we had to replace the fuel lines going to the generator.
  • gbopp's avatar
    gbopp
    Explorer
    Jun 17, 2016
    Did you change the fuel filter lately?
    I solved a surging problem on our Onan 5500 by changing the fuel filter.
  • snarley's avatar
    snarley
    Explorer
    Jun 17, 2016
    Very similar sounding problem to what I had- turned out to be fuel pump because of very high air (+95 deg F) temperatures- changed the pump, less than $ 50 thru Amazon, and been OK for two plus years.Story is some made in China fuel pumps are known to have this issue.
  • jwmII's avatar
    jwmII
    Explorer
    Jun 17, 2016
    Check the rubber fuel line from the tank to the gen. fuel pump. Yours is 15 or so years old and probably dried out and cracking. This lets the fuel pump suck air along with some fuel and eventually it cannot keep up with the engine fuel requirements and shuts it down.

    While you are in there check the other rubber lines going to and from the tank as they are due for replacement as well.

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