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Fuel priming Onan mdl3 generator-gctid815668

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    Fuel priming Onan mdl3 generator-gctid815668

    I replaced my Racor filter which does not have a priming pump on top. Since then I have not been able to get the generator to go. I unplugged the line from the filter to the generator and filled it with fuel. I also used a pump to prime the fuel to the filter. I of course filled up the Racor with fuel. Got it going for a few seconds but no more. I also followed the procedure in the instruction manual to use the manual priming on the generator. Is it normal that I feel no resistance on the generator priming lever? Is it possible the fuel pump is defective?

    #2
    Were you having problems with the generator shutting down before changing the Racor? If so, it could be the electric fuel pump. Ours deteriorated to the point it wouldn't pump enough fuel. Replacing it fixed the problem. The pump was around $100 if I recall correctly.
    Mike
    "Allante I" Rayburn 75
    Previous: '97 4788

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      #3
      "WhiteRockMike" post=815687 wrote:
      Were you having problems with the generator shutting down before changing the Racor? If so, it could be the electric fuel pump. Ours deteriorated to the point it wouldn't pump enough fuel. Replacing it fixed the problem. The pump was around $100 if I recall correctly.
      It was hard to start, but once it was going it would not stop. Someone mentioned to me it might be an electronic switch causing the hard start. As for the pump, it's not an electric one, it activate by the engine. I figure with the age of the genny (1988) and the 4000 hours on it that something could be broken or loose inside.

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        #4
        Fox,

        My boat is a 1989 with an original Onan genny. It definately has an electric fuel pump which required replacement recently due to external leakage. I might double ck yours for an electric pump.

        As for the difficult starting, are you pre heating? Is the pre heat system functioning properly? An easy down and dirty test is to monitor the genny start battery voltage when you activate the pre heat, look for a drop in voltage.
        Jim Gandee
        1989 3888
        Hino 175's
        Fire Escape
        [email protected]
        Alamitos Bay, SoCal

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          #5
          Had that issue in the past with our onan Mdl3, about 3 years ago add a basic electric fuel pump inline form napa before Racor to push fuel to MDL3 and that allows you to bleed the entire line and engine and it filter.

          We just remove and almost done installing a new gen set Fisher Panda 15kw, and for what it is worth is also came with a small fuel pump to put in the exact same location as we had the above, the mechanic helping with the installs says most new gen sets are doing this.
          Mark
          USCG OUPV
          1990 4588
          Carlsbad, CA

          Comment


            #6
            "Destiny 4588" post=815884 wrote:
            Had that issue in the past with our onan Mdl3, about 3 years ago add a basic electric fuel pump inline form napa before Racor to push fuel to MDL3 and that allows you to bleed the entire line and engine and it filter.

            We just remove and almost done installing a new gen set Fisher Panda 15kw, and for what it is worth is also came with a small fuel pump to put in the exact same location as we had the above, the mechanic helping with the installs says most new gen sets are doing this.
            I went a similar route, but with a manual pump at the end of the line. Worked and I got the gen started. I used a pump that you normally use to fill oil into the foot of an outboard and pump until there were no more bubbles then plugged the line back in. Here are the pics from the service manual. I actually have all service and parts manuals for the gen and the Hino engines (previous owner got them when he bought the boat in 88). I should scan them and put them online for people who don't have them.

            [attachment]38807 wrote:
            20170703_114558 - Copy.jpg[/attachment]

            [attachment]38808 wrote:
            20170703_120300_resized.jpg[/attachment]


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