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  1. #1
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    1968 Johnson Outboard Issues

    My flatbottom has a 1968 Johnson 9.5 horse on it. When it's in the water and you turn it to full throttle it'll just idle. Sometimes you can put it in neutral and it will rev appropriately and sometimes it won't. As a test, I put it in gear and it did it's typical idle thing at full throttle. I left it running and pulled it out of the water, put it in gear and revved it and it revved appropriately. So I guess either water is screwing something up, or it can't pull itself when it's under a load. But, half the time in the water it will just idle in neutral as well when you rev it to full throttle.

    I have been through everything in the motor. It fires appropriately, looks like the points are set appropriately (I took it to someone and had those set to double check myself), plugs are new and fire appropriately, so I guess it's a fuel issue. But, it appears to be getting gas fine in the carb. Ran a can of sea foam through it with no results. Any ideas?

  2. Ohio Fishing Reports Moderator omcforever's Avatar
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    #2
    Have you done a compression test? I would start there.

    Age and treachery will always overcome youth and skill !!

  3. Ohio Fishing Reports Moderator omcforever's Avatar
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    #3
    If that checks out(what where the numbers), I would do a link and sync per a real OMC service manual. Check basics first. Have the carbs been gone thru with new kits per the manual? Are you running a quality fuel filter between the tank and motor?

    Age and treachery will always overcome youth and skill !!

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    #4
    Possible coils. Look for cracks in the epoxy. They will pass all tests but won't fire under compression.

  5. Ohio Fishing Reports Moderator omcforever's Avatar
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    #5
    What I have seen in the past is that older motors that run off a remote tank are prone to carb issues because most just run em and never really clean the the tank or fuel system or really maintain them properly. Serviced a lot that had carbs gunked up/orifices clogged/transfers clogged. Tanks full of rust and dirt,,,,ect. Check lines from tank as they are probably old and not ethanol resistant and could be bad s well. Again, start with a compression check.

    Age and treachery will always overcome youth and skill !!

  6. Ohio Fishing Reports Moderator omcforever's Avatar
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    #6
    Seafoam cures nothing,,,,LOL

    Age and treachery will always overcome youth and skill !!

  7. Ohio Fishing Reports Moderator omcforever's Avatar
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    #7
    New boat to you? Just start doing it or gradual????

    Age and treachery will always overcome youth and skill !!

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    #8
    Thanks for the input guys. I've had this boat for several years. I replaced the lines not too long ago because they were looking a little rough. It's been a while since I've done a compression test, so I'll try that again. It ran fine for a long time and then it gradually started doing this and has just gotten worse really. The carburetor having junk in it was one of the first things that I thought of. When it first started doing it, I stopped and revved it max in neutral. It sputtered for a few seconds and then opened up correctly and ran fine for a while. I have replaced coils a couple times, but that doesn't mean that the one on it currently is working correctly. I'll start with the compression test and then probably the carb. Thanks again for the info guys, much appreciated.

  9. SC Club Moderator ChampioNman's Avatar
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    #9
    Quote Originally Posted by omcforever View Post
    Seafoam cures nothing,,,,LOL

    Yes it does everything from gangrene to epilepsy.

  10. Ohio Fishing Reports Moderator omcforever's Avatar
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    #10
    Quote Originally Posted by ChampioNman View Post
    Yes it does everything from gangrene to epilepsy.
    Hemorrhoid's?

    Age and treachery will always overcome youth and skill !!

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    #11
    That would require WD-40

    2016 Phoenix 921 ProXP Mercury 250 ProXS

  12. SC Club Moderator ChampioNman's Avatar
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    #12
    Have you checked your shear pin?