Help needed with mercury outboard

Discussion in 'Bubba's Outboards' started by neocats, Aug 17, 2009.

  1. neocats

    neocats New Member

    Messages:
    2,130
    State:
    Steubenvil
    I have what I think is a 1989 40hp Mercury outboard that doesn't run right. To start with, it won't plane off.....has no power. When I hit full throttle, it bogs down like it is getting flooded and will die. It is sometimes hard to start and at other times it fires up on the first bump of the key.

    Where should I start looking to figure out the problem?
     
  2. CatHunter24

    CatHunter24 New Member

    Messages:
    715
    State:
    Dayton, Ohio

    Had the same problem with my 50 or at least they sound similar. We rebuilt the entire fuel system...and tried to adjust hte carbs and the idle and still had no luck. :angry:. I wish you the best on this problem...wish i could give you ideas but we ended up being stumped. I just bought a 90 Yamaha to replace it....got fed up.
     

  3. Bobpaul

    Bobpaul New Member

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    3,039
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    First time reader?

    It's been said, over and over. Diagnostics starts with a spark check, and a compression check. Without that information, your working blind.

    If that's good, then there's a fuel issue.
     
  4. neocats

    neocats New Member

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    2,130
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    Steubenvil
    Spark and compression were checked and are good.
     
  5. tbull

    tbull New Member

    Messages:
    3,318
    State:
    SW Ohio
    If spark and compression are good its safe to assume we have a fuel problem. Have the carbs ever been cleaned and rebuilt? If its flooding that may be the case.
     
  6. Bill in SC

    Bill in SC New Member

    Messages:
    4,451
    State:
    South Caro
    If it's flooding, it sounds like a possible needle and seat problem. Very simple fix with a carb cleaning.

    Bill in SC
     
  7. neocats

    neocats New Member

    Messages:
    2,130
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    Thanks guys. I will first start by replacing the rule line, and then go into car cleaning/rebuilding. This is still new to me and rebuilding a carb is something I have never tried. Hell, I have never taken this one off the motor yet.
     
  8. Bill in SC

    Bill in SC New Member

    Messages:
    4,451
    State:
    South Caro
    It is a VERY SIMPLE job, Jeff. You will have NO problem. I think a rebuild kit is just a gasket and needle and seat. Yours might just need cleaning though. I'd look it over before I bought any kit.

    Bill in SC
     
  9. neocats

    neocats New Member

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    2,130
    State:
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    Could an old fuel line from the tank to the motor cause this problem?
     
  10. Bobpaul

    Bobpaul New Member

    Messages:
    3,039
    State:
    Supply NC
    Replace the old fuel line, but doin't stop there. Get the carbs cleaned, check all your other fuel lines and replace if questionable.

    Get your serial number from the engine to get the proper parts. Don't half ass it, get carb kits.
     
  11. Absoloutely, if your going to dig into the fuel system, get it all done, and it aint' that complicated. Start off at the tank and drain it completely. You want to get all the dirt and water off the bottom that you can.

    If the lines are older than 2 or 3 years, replace them. When they swtiched over to the new fuel with ethanol mixed in 2 years ago, it wreaked havoc on any older rubber parts in the fuel system, especially the rubber lines. Throw some new ones on with new clamps, and if ya got the room and a few extra bucks, throw on an inline filter/water separator.

    Check your fuel pump. Get a kit and relpace the gaskets and stuff, very easy. Even if ya just take it apart and clean it out, some have a screen in there that clogs up with dirt.

    Then ya get to the carb/s. You gotta search for it here, but there is an excellent section on here for the process of rebuilding a carb, and is very well explained with pics and everything.

    When ya refuel, I use a few ounces of dry gas at every fill up, and an ounce or two of Marvel Oil once a month to keep the rings nice and loose.

    Good luck.