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1988 9.9 with 15 hp carb.. no power

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  • 1988 9.9 with 15 hp carb.. no power

    Ok I have this 9.9 that I found out had a 15 hp carb. I found out cause it never had full power never got above 4000 rpms. After taking the carb out and rebuilding it 100X I started to lose it.

    So so I have 3 high speed jet plugs and don’t know which one to use... they have a 50 , 54, and 55 stamped on the side.

    i believe it originally came with the 54 which according to my research was for the extended longbshaft sel model sail boat one ... I’m thinking that’s what this carb came off of. Is that why it never ran right?

    Its the newer carb with palstic bowl and plastic top

    after i put this carb back together and have the same issue, what should I do next?

    Compression is 120 each, my spark tester is cheap so I’m not sure how strong it is.

    can you check the spark strength by using the plugs?

    If its not the carb what else could it be? Thanks in advance
    Last edited by BlackoutBill21; February 9th, 2019, 08:55 PM.

  • #2
    Is the spark advancing as the throttle is opened? If adjustable, is the max timing advance correct? Was a link and sync done when the carb was reinstalled? Sometimes there are more differences between the 9.9 and the 15 than just the carb, which are needed also to take advantage of the bigger carb and result in greater HP

    As for the jetting. you are going to have to make friends with a Partsperson at a Dealership and get him/her to see if they can find what jetting the carb needs

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    • #3
      Yeah to all of that. Link and sinc done numerous times .

      All I wanted was a long shaft 10 hp motor lol I got stuck with this Frankin motor. If a 9.9 carb wasn’t so much money I’d buy one. Would love 11 hp or more or whatever the 15 carb would put out but I’d rather it ran correctly

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      • #4
        my research says the 50 is for 9.9's. maybe not prop'ed right?

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        • #5
          plastic top carb have bigger cam folower roler,
          and make sure that which one of oriface plug do you have?
          this oriface plag is 0334014 for 15 hp model and 0334025 for 9.9
          difference is in diameter. i have to check in my notes which one is for 9.9 and 15
          Last edited by jbcurt00; February 10th, 2019, 05:13 AM.

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          • #6
            The parts diagram for the 15 hp carb says the #55 is for that carb. 50 is for the 9.9 which I have but the carb is 15 hp. The 54 days for the sel model.

            Racezkpe1 bigger roller should I swap out the roller for another? Of just check my link and sinc?

            Juno: I was worried about that so I bought a new prop which I haven’t been able to test yet in NJ. This season for sure...

            also. I read in the ramblings that this carb like it rich... like 4 turns out to start... should I start with the 1-1/2 instead? I rarely had an idle or starting problem

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            • #7
              Rebuilt the carburetor 100X-----I say it is not a carburetor problem !-------Reed valves checked ?-----Intake manifold gaskets installed correctly?----Fuel pump diaphragm checked ?----Flywheel key checked ? -----Ignition advancing properly ?------Exhaust passage way clear ?------Cam that opens carburetor throttle plate the correct one and not broken ?----Bottom crankshaft seal checked ?

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              • #8
                I’ll have to check all that next. I had it in the barrel and it ran beautifully. But what I’ve noticed since I’ve had it, no matter how much I messed with the carb the main issue aside from power was that when you go from idle or trolling to high speed it wants to and will stall unless you ease into full speed.

                any ideas why?

                Comment


                • #9
                  should see something around a half inch, sharp spark. Need an open air adjustable tester to test magneto strength.

                  The carb has an idle adjustment needle, or should have for '88. One of the adjustment test is stalling on throttle up -- might try setting the air mix a little richer (counter clockwise) and see if operation improves.

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                  • #10
                    Thanks old boat. I’ll use my crappy spark tester and richen the non up a bit. I have it at 2 turns out. That’s where she won’t stall at idle on me

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                    • #11
                      just curious

                      did you or can you check with previous owner if this thing ever ran properly …..

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                      • #12
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                        Originally posted by BlackoutBill21 View Post
                        I’ll have to check all that next. I had it in the barrel and it ran beautifully. But what I’ve noticed since I’ve had it, no matter how much I messed with the carb the main issue aside from power was that when you go from idle or trolling to high speed it wants to and will stall unless you ease into full speed.

                        any ideas why?
                        That sounds like a Leaning out or a problem regarding the spark/carb sync.

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