Merc 115 Stuck at 2000 rpm

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  • Merc 115 Stuck at 2000 rpm

    So I have an 89 Mercury 115 2-stroke. Serial Oc106309.

    Ran normal for most of the weekend. Slow trolled for a bit and when I opened it up it wouldn't go past 2000 rpms for probably 30 minutes. Bumped up to 3 grand from 30-40 minutes and then opened up all the way and ran faster then it has since I've owned the boat. So about 50 minutes of limited rpms then ran like a taped ape.

    Recently changed the impeller and temp sender. Had a very brief alarm go off at the beginning of the second day of our trip that was a solid beep for several minutes, went off and then screeched and chattered for a couple minutes a little later

    Thanks for any help!

  • #2
    On my 96 225, solid alarm is overheat alarm.
    Small town S. W. Ga./St. James Fl.

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    • #3
      My 96 Mercury also has a continuous horn at overheat.
      My 115 is a 4 cylinder, yours is probably a tower of power 6.
      BWP

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      • #4
        Also, you may want to check fuel pressure. A lean condition will make an engine run hotter.
        Small town S. W. Ga./St. James Fl.

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        • #5

          Cleaned all 4 carbs and replaced both fuel filters. Took it to the lake where it seemed to be running normal but ended up getting stuck at 1500 rpm later in the day and was running very rough.

          Trailered it and pulled the plugs, all 4 which were fouled with oil residue. Cleaned them with some carb cleaner and a rag and went back out. Was immediately capped at 3000 rpm with the throttle wide open, so better but still garbage. Called it a day after that.

          Any ideas?

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          • #6
            Are you mixing oil/gas or running the vro?
            Small town S. W. Ga./St. James Fl.

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            • #7
              I'm curious, still not sure as the 6 was in it's last leg in late 80's, not sure when the 4 cylinder came out as I have the 1996 version, if yours is this it's a strange animal.

              mine ran on 3 cylinders for a long time till I replaced the switch box, again!
              the grommet on my poppet valve was constructive and I enlarged and no more overheat.
              Ask away!
              BWP

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              • #8
                You may be able to find the old service manual on www.boatinfo.no I was not able to scroll with my phone to check your serial number with what is there.

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                • #9
                  Originally posted by ajtec View Post
                  You may be able to find the old service manual on www.boatinfo.no I was not able to scroll with my phone to check your serial number with what is there.
                  Boatinfo looks like a shady site. Lots of dead ends.

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                  • #10
                    Originally posted by Pstephens46 View Post

                    Boatinfo looks like a shady site. Lots of dead ends.
                    I have been pulling up old service manual info there for 15 plus years for various old motors. Probably even longer then that. Generally this has been for the Mercury books I did not have and Volvo. It runs in an old platform and has always looked the same. It does not function with cell phones very well.

                    For old OEM books it was always been a good resource. For new stuff, it has never been updated.

                    You click on the books, then the word Manuals, then Mercury. The slide bar scrolls through the books.

                    I’ve only ever used it for Service Manuals.

                    Use it if you want but it has never caused an issue for any of my company computers.

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                    • #11
                      Looks like it still works and I am thumbing through the actual OEM book for the engine mentioned above. If I hadn’t found it way back when I would be sceptical too.

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                      • #12
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                        • #13
                          For curiosity I searched “boatinfo” and separated the “.no” on google. It appears when the site goes down the forums light up with people wondering why.

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                          • #14
                            Ah! You have the 2+2, good job, idles on top 2 and around 18-2000 rpm the bottom 2 kick in and it jumps onto plane!

                            I've replaced switch box twice on mine, in 4 years.
                            Max is 5250 as it's an unbalanced design.

                            I've just discovered upper engine mount rot and no idea what I'll do next.
                            oh well, B.O.A.T.

                            BWP

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                            • #15
                              Originally posted by ajtec View Post
                              For curiosity I searched “boatinfo” and separated the “.no” on google. It appears when the site goes down the forums light up with people wondering why.
                              Fair enough.....phone is the issue I’m sure.

                              We had a good awhile back for Yam manuals. Must have hit the radar and it got shut down. Now we gotta rely on Jethro1 and no telling what he may be up to.

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