45 HP Merc needing high speed adj or cleaning

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  • July 8, 2015 at 1:55 am #1960
    karlsmercs
    Participant

      Working on a friends 1989 45 hp Merc, 3 cylinder and dual carb. I think it’s only putting out about 25 hp. I see no high speed adj so I suspect there is a high speed fixed jet. Thinking that 1 or the 2 carbs has a problem at mid and high rpm relating to the high speed jet. This lack of take off power and sluggish top end leads me to this.

      July 8, 2015 at 9:44 am #19651
      chinewalker
      Participant

        US Member

        Take them apart and clean them. New, ethanol resistant kits should be installed while you’re at it.

        Also, compression and spark checks should be done.

        July 8, 2015 at 3:32 pm #19665
        jeff-register
        Participant

          US Member - 2 Years

          That old check the fuel system for any leaks. Should hold pressure while not running & will be soft running as it is passing fuel. Do not get the carbs mixed up on the engine, keep the top & bottom one the same. Check your timing too. Pull your plugs right after a run & look for moisture. The bottom seal might be bad

          July 9, 2015 at 1:16 am #19705
          karlsmercs
          Participant

            Thanks guys. All good tips to check out this week. I had pulled the plugs. They didn’t show signs of water but I’ll check again next time it’s run. It idles nice and at slow speeds purrs where a bad water jacket would be more throughout all speeds. I will check compression. If all above seem ok then I’ll get to tearing down the carbs and good point not mix the positions up.

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