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supercub's avatar
supercub
Explorer
Dec 10, 2017

Onan 7500 diesel gen........no starter

Press the gen starter button on the dash or on the gen itself and no starter.........can hear it chat chat chat.........which I believe is the fuel pump. Is the starter bad....or could it be something else? I haven't done any checking yet. Thanks
  • are you holding the start switch down long enough for pre-heat? if it is chilly out it may take about a minute before it starts turning over.
  • Hold it down for a couple of minutes. I have the same thing with my Onan QD
  • Thanks for the input...........Easist fix I have ever had.............I just held the switch down a little longer and ..........presto.........it started LOL.
    Thanks for the suggestions.
    Brian
  • supercub wrote:
    Thanks for the input...........Easist fix I have ever had.............I just held the switch down a little longer and ..........presto.........it started LOL.
    Thanks for the suggestions.
    Brian


    Brian,
    You don't say what coach, model, year etc. The Onan 7.5QD (and just about any other model of Onan RV diesel gen) is governed by a small ECM that controls all of it's operation. And, not only that but, there is what's called a temp sensor in the cooling system that, sends signals to the ECM, telling it what present operating temps the engine is at. That temp sensor not only sends signals for COLD operations but, also HOT ops too.

    The little Kubota engine that powers the Onan QD is a 3 cylinder, 14 HP engine and, uses "Glow plugs" for preheating the cylinder combustion areas, prior to starting, especially in colder weather.

    There is a time delay chart that Onan prints in it's maintenance and ops manual that tells how long the glow plugs must be heated, prior to the starter receiving a signal, to start to turn the engine over.

    The colder the climate, or, ambient temp, the longer the glow plugs must heat, prior to cranking. I've posted the chart several times. And, it's not MINUTES. The max time for glow plug heating is around 15 seconds or so. So, in colder conditions, as in say, oh, about 40 or so degrees outside, the starter button must he held for the longest time frame in the chart, before the ECM, will allow the engine to be cranked over. The warmer the climate is, the less time for heating. As in, if it's around say, 65-70 degrees outside (which would mean the coolant in the engine is about the same temp), the glow plugs will not need preheating, the starter will engage immediately when the button is pushed. Hope this clears things up a bit.
    Scott