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2003 Merc 20hp 2 stroke bogs only at WOT

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  • 2003 Merc 20hp 2 stroke bogs only at WOT



    The motor runs like a champ and has been well maintained. Lately, when running at WOT, after a minute or two, it bogs down. If I back off the throttle a little, it runs fine. Another action that will bring it back to full RPMs is to pump the primer bulb in the fuel line. (The bulb never really does get hard.)

    It's the original Merc gas tank and silver fuel line. BTW, for years, I've only been running non-ethanol gas.

    I suspect the fuel line or at least the bulb, and don't want to replace parts unnecessarily. What do you recommend?


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    Completed condensed version: The Permanent Vacation

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  • #2
    Rebuild the fuel pump, LL.

    Over time the diaphragm stretches and can't deliver the volume needed. WOT bog and bulb squeeze are the clues.
    BOAT SPECS FORUM HELP STARCRAFT FORUM SHOP iboats
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    • #3
      This may be a double post, I'm at the lake on my phone where the reception is variable at best. Repair manual is at home too.

      What about the fact that the bulb never gets firm even before starting? Do you think that might be a factor?
      My project (with index): 1964 Jet Star: https://forums.iboats.com/forum/boat-...nabout-project

      Completed condensed version: The Permanent Vacation

      Make a New acrylic windshield: https://forums.iboats.com/forum/boat...craft-jet-star

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      • #4
        Rebuild the whole carb. Get the kit that has the primer, fuel pump diaphragms and all gaskets. The fuel pump on that motor is part of the carb.

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        • #5
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          Thanks for getting me pointed in the right direction, guys.
          My project (with index): 1964 Jet Star: https://forums.iboats.com/forum/boat-...nabout-project

          Completed condensed version: The Permanent Vacation

          Make a New acrylic windshield: https://forums.iboats.com/forum/boat...craft-jet-star

          Comment

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