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  1. #1
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    Default Magnum 18 Fuel Pump Failures

    I have just replaced my 3rd fuel pump in two years (Cub 1872) and have had it! Why would anyone specify a plastic body on such a part!? (I know . . . so you will have to buy new ones.) Anyway I'm going electric, such as a Facet pump, and wondered what the others of you have done, the pumps you've use, where you connected the power lead, and the results you've had.
    Harry
    Nashville TN
    129 and 1872

  2. #2
    Gold Member diesel_nut's Avatar
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    ~'88 1872(sold); '08 GT2554

    Default Re: Magnum 18 Fuel Pump Failures

    just sold my 1872 after 6 years of ownership. The pump never went out on me. I guess you are just 'lucky'.
    Cub 1872(SOLD); Cub GT2554

  3. #3
    Silver Member moe1942's Avatar
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    Default Re: Magnum 18 Fuel Pump Failures

    You can solve your problem by installing an electric fuel pump.

  4. #4
    J_J
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    Super Star Member J_J's Avatar
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    JACKSONVILLE, FL
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    Power-Trac 1445, KUBOTA B-9200HST

    Default Re: Magnum 18 Fuel Pump Failures

    I had Magnum 18 HP on my smaller Dixie Choppers, and never had any trouble. What part is defective.

    That is a mechanical fuel pump with check valves, a diaphram, and a lever. You have to be sure that the lever is above the cam shaft to work properly. If the gas tank is above the engine, you probably can run it with gravity feed and remove the fuel pump, just put a cover on the opening.

    http://www.kohlerengines.com/manuals/landing.htm

    Select Magnum then, 18 HP engine, then select English, and then it will give you a PDF file to open.
    Last edited by J_J; 05-12-2009 at 10:15 AM.
    J.J.

    When I works, I works hard. When I sits and thinks, I goes to sleep.

    Git er done.

  5. #5
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    Default Re: Magnum 18 Fuel Pump Failures

    Thanks for the suggestions . . . here is what I found when running a few tests . . .

    First, the recurring problem has been leakage around the metal (brass) thrads of the fuel line barbs in the pump head. The head gets hot, expends a bit and the fuel leaks. Tighten the barb by one turn to seal the leak, or add teflon tape, and next thing you know the housing has split. The last two replaced pumps have microscopic (or not so microscopic) splits in the thread housing. Various thread sealers did not hold. Anyone ever tried making copper to PVC pipe connections using just plain old threaded fittings? That doesn't work reliably either.

    In checking around I found that the cube type electronic (as opposed to electric) fuel pumps, like the FACET/Purolator pumps, have a record of quick failures. The British motorcycle guys seem to like them a lot but they also say the pumps in the UK are different somehow from those sold in the US, anyway most of the reports over here say they won't stand up to mower duty very long, a matter of hours in some instances. I might get lucky but with typically only a 30 day warranty that's not a very smart bet.

    OK back to the Kohler pump, . . . somewhere in one of my searches I read the word "redesigned" so in hopes they had changed to a metal housng (a futile hope of course) I went back to my local parts house and looked at a fresh pump. The redesign is this, the old metal thread connectors have been replaced by all-plastic snap-in connectors which use an O-ring seal. No expansive pressure is put on the pump housing and the barbs are held in place by a built-in snap ring device. Very nifty. The pump swap took 15 minutes.
    Harry
    Nashville TN
    129 and 1872

  6. #6
    J_J
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    Default Re: Magnum 18 Fuel Pump Failures

    My Magnum 18's have always uses a 1/4 in tube to pump with spring clamps to secure the line to the fuel pump. and I used those engines sometimes 6 to 7 hours a day on my small 42 in Dixie Choppers. Like I said before, if the tank is above the carb, then gravity feed will work.
    J.J.

    When I works, I works hard. When I sits and thinks, I goes to sleep.

    Git er done.

  7. #7
    Veteran Member Iron Horse's Avatar
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    Orstraya , Ex convict stock , G'day .

    Default Re: Magnum 18 Fuel Pump Failures

    Maybe you can buy plastic barbs to replace the Brass ones . As you have found out , the plastic housing and the Brass barbs expand and contract differently with heat . Also , Teflon tape and liquid Teflon sealers on a tapered thread will crack a plastic or die cast housing as they act as a lubricant and allow the tapered male thread to force the female thread to expand and crack .

    On edit , i see you have now fixed it .
    Last edited by Iron Horse; 05-14-2009 at 07:01 PM. Reason: Blind .

  8. #8
    Silver Member moe1942's Avatar
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    GT2542

    Default Re: Magnum 18 Fuel Pump Failures

    Doesn't sound like you are doing that great with the OEM pump.

  9. #9
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    Default Re: Magnum 18 Fuel Pump Failures

    I had the same problem on my 1810 when I put in a new Magnum 18 block last winter. The plastic housing cracked when I tightened down the gas line. Lo and behold the replacement pump has been redesigned so that the connection to the fuel line is metal so that it won't split when you screw in the metal thread piece on the end of the fuel line and the connection to the fuel pump is a quick connect so Cub Cadet knew they had a glaring design defect on the pump and fixed it.

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