Need help with my Johnson 4 hp. Won't run for more than 1 minute

Discussion in 'Outboard Maintenance' started by zeneb, Jun 25, 2011.

  1. zeneb

    zeneb River Hawk 15'4" 15HP Evinrude / 15 HP Merc

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    I thought I had the ole Sea Horse running, but when I took it out today it wouldn't run for more than just a minute or two. It started pretty quickly the first time, which I took as a good sign. It runs strong, then just dies, like it isn't getting gas. I messed with the mixture and it didn't matter.

    Hooching
     
  2. Brett

    Brett > PRO STAFF <

    Ok, so find out why it isn't getting gas.
    Anti-siphon valve malfunction?
    Air leak?
    Fuel pump diaphragm punctured?
    Float valve stuck?
     

  3. zeneb

    zeneb River Hawk 15'4&quot; 15HP Evinrude / 15 HP Merc

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    My neighbor, who's much more of an engine guy than I am, came over today. We gapped and cleaned the plugs, checked and cleaned the fuel pump, and we were still having issues. It looks like the pump is working fine. There may be some air getting in the line, but i*m not sure. It sounded much cleaner after we did the cleanup. I am going to take it to a mechanic and see what he says.

    Hooching

     
  4. Brett

    Brett > PRO STAFF <

    Have you tried simply hooking it up to another fuel tank and line with fresh fuel?
     
  5. zeneb

    zeneb River Hawk 15'4&quot; 15HP Evinrude / 15 HP Merc

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    Swamp Angel and I hooked it up to his tank when we had it out the first time.  It worked fine for as long as we had it running, but it was only for a few minutes.  I had it running at least as long as he and I did today so I can't prove or disprove anything by it.  I'm sure the mechanic will have one around so we can remove that as the problem.  One thing that he and I were messing with some is the vent on the gas can itself.  Is it supposed to be closed, open or tuned like the carburetor? He is used to a spring loaded vend and the one on this tank is twist to open/close.

    Hooching
     
  6. Brett

    Brett > PRO STAFF <

    Vent should be open when outboard is running.
    Otherwise the vacuum pressure that forms in the tank
    will be stronger than the pressure developed by the pump.
    No fuel gets to the carb.
     
  7. schiley1

    schiley1 I Love microskiff.com!

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    x2 Brett, I had a 3.5 suzuki outboard, would run great at idle till it ran out of gas, if you ran it faster it would die, cleaned carb, took it out again,same result,motor would start back up after about 4-5 min. then die again, took carb apart again,tried again, this time though when I was opening vent in cap the piece on top that you twist on top of the cap twisted off, it looked like the plastic had degraded, tried loosening entire cap and motor ran great. so I had to buy a new cap. Didn't have any problem after that. So lesson learned, you need gas, spark and air, without any one of them motor will not run or in my case run very long. Ed
     
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