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  • Loss of speed

    Hi, I have a 70hp outboard. I always get 21 mph at top speed , no problems. The last few trips it maxes out at 14 mph and will not go higher. Any solutions?

  • #2
    fix it.

    someone will have to test things to find what the problem is.

    can you or have you tested anything

    if not you, then you need to take it to someone that can

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    • #3
      Solutions? Yes, the solution offered above is the one that is guaranteed to work for you (have someone fix it, that is). Besides, that, it's awful hard for us out here in interspace to figure out what's going on based on the info you've provided.

      An often over looked cause can be a dirty bottom... of the boat, that is. Even just a thin slime layer can do it. Other times there's something wrapped around the lower unit. Other than that, you're basically looking for the proper fuel supply (of FRESH fuel), good spark and enough air (air is almost never the problem.

      Oh wait... I thought of another possible cause for the problem... you've put on A LOT of weight since the last time you were out in the boat!
      Last edited by DennisG01; 06-26-2017, 08:29 PM.
      2000 Yamaha OX66 250HP SX250TXRY 61AX103847T
      1982 Grady Weekender/Offshore (removed stern drive & modded to be an OB)

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      • #4
        We were working on a similar situation last week. We checked coils, timing, cleaned carbs....nothing helped. Finally did an overnight Seafoam decarb and it woke back up. I'm thinking it had a stuck ring.

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        • #5
          I guess checking he simply things would be the easiest start, short of losing weight lol.

          Any recommendations of the top 5 things to check out before taking it to a service place who will randomly check by elimination and charge for everything it is not ?

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          • #6
            Remove and inspect spark plugs....may be one fouled...easy fix. Of course a partially plugged carb jet could cause you to lose power. Drain each carb float chamber onto a clean rag to look for water or debris...

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            • #7
              Thanks going to try and will get back

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              • #8
                compression is where I normally start, inspect plugs while they are out.
                check spark on all cylinders and the timing.
                Timing light will make both of those easy.


                if all of that is good then deal with fuel

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