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1997 Evinrude 9.9, Loss of Power after about half throttle.

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  • 1997 Evinrude 9.9, Loss of Power after about half throttle.

    I just acquired this motor. It was recently found in a garage, and appears to be near new. The original spark plugs hadn't even ever been removed. The motor is spotless, not a scratch on the skeg or prop. I was able to tank test it from the guy I bought it from and it seemed fine, although I only started it and ran it up to about half throttle.

    I took it out today and it starts and runs pretty well up to about half throttle. Any higher than half throttle and the motor begins running poorly, sputters, will rev up and down from half to maybe about 3/4 power. I have brand new gas tank, and hoses. The bulb stays hard. The plugs seem fine, not fouled or wet. I backed out and tried various positions on the accessible carburetor adjustment screw, with no change, except I got it to idle a bit better. The carb is secure.

    I'd like to know what sequence I should go through for troubleshooting this? I have very limited tools at the moment. My family is arriving here in 10 days and I need to get this fixed before they arrive! My funds are minimal so taking it to a mechanic is a last resort.

    Right now I'm going to the store to get some carb cleaner and canned air. I'll pull the carb and clean what I can and make sure the float works and so on.

    Any help is so very appreciated!

    Thanks
    Akfish42

  • #2
    Re: 1997 Evinrude 9.9, Loss of Power after about half throttle.

    Disassembling the carb and cleaning is the first step.

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    • #3
      Re: 1997 Evinrude 9.9, Loss of Power after about half throttle.

      You may try replacing the fuel filter first. with a dirty filter the motor will idle and run at slower speeds just fine, then when you increase the throttle the debris will clog up and cause the carb to not get enough fuel and sputter. I see this happen quite often.

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      • #4
        Re: 1997 Evinrude 9.9, Loss of Power after about half throttle.

        Hmmmm, I did check the screen on the fuel pump. I don't think there is any other fuel filter? Should I pull the fuel pump off and disassemble for cleaning?

        Thanks

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        • #5
          Re: 1997 Evinrude 9.9, Loss of Power after about half throttle.

          If the pump is working, I wouldn't disassemble it. Bring a squirt bottle of premixed fuel with you next trip and squirt a little in the carb when it fails. If it gets worse, you're having a flooding condition, if it get's better, it's likely a blockage in the carb. If it is a flooding condition, perhaps you have a small tear in the fuel pump diaphram and fuel is dumping directly into the cylinder that it draws it's pulse from, effectively flooding out that cylinder. You can test by pulling the 2 mounting bolts from the fuel pump and pull the pump off it's mounting gasket, leaving the hoses connected. You need to find 2 nuts to then put on the mounting bolts and cinch them to the pump itself so the pump is now isolated, and all bolted together like when it's mounted. squeeze the fuel bulb and see if any fuel comes out of the 'pulse' hole in the back of the pump. If there is, you have a bad pump diaphram. Good luck!
          author unknown: It's almost beyond the point of bearable how torturous it is to try to have any dignity in being a Vikings fan..

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          • #6
            Re: 1997 Evinrude 9.9, Loss of Power after about half throttle.

            Also, be certain you have the correct spark plugs and they're gapped at .030".. and the plug wires aren't cut/damaged.
            author unknown: It's almost beyond the point of bearable how torturous it is to try to have any dignity in being a Vikings fan..

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            • #7
              Re: 1997 Evinrude 9.9, Loss of Power after about half throttle.

              Thanks, I'll check this after I get the carb back on. I just got it off, had to grind down an open ended wrench to get to the inside mounting nut (major pain). The carb looks like the rest of the motor, pristine. I'm going to pull the bowl and look at what is listed as high speed orifice, i'm hoping there is an obstruction there. Thanks again!

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              • #8
                Re: 1997 Evinrude 9.9, Loss of Power after about half throttle.

                On my '88 evinrude 150, I had a similar problem. Mine has a mechanical linkage that changes engine timing with throttle position. There is an arm under the flywheel that can slide back and forth about an inch. The throttle position has a small mechanical linkage rod that ties to this timing arm. The connection is a little piece of plastic that clips on and does nothing more than tie the rod end to the timing arm. This little piece of plastic cost me some rediculous amount of like 50 cents, but cost me an hour of time and stress trying to limp my boat back to the dock from the middle of the lake. I found it through luck, it was not immediately apparent to me what the problem was. Not sure if your motor has the same type of set-up, but if so, hope this helps!

                Aaron

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                • #9
                  Re: 1997 Evinrude 9.9, Loss of Power after about half throttle.

                  Hey Aaron, yeah my motor has the same set up. Mine seems fine as I have removed and installed it twice now. I just put the carb back together, it was literally pristine, not a smudge of anything on or in it. I really don't think this motor has been used much or at all. I also checked the fuel pump, as per "kbaits" guidance, and it seems to be fine. The one thing I did find was that the fuel line going to the fuel pump was a bit too long and was somewhat kinked where it made a bend, so I shortened it to remove the tight bend. Could that actually be the problem? Holy Mokus I hope so! I'm off to the river for a test run!

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                  • #10
                    Re: 1997 Evinrude 9.9, Loss of Power after about half throttle.

                    I tried you suggestions, the fuel pump seems fine, the carburetor is clean as a whistle, I took off the air box and sprayed gas with little effect, except to bog the motor down if i sprayed in too much. The plugs are like new correct type and gap. What next? I'm thinking it must be an electrical gremlin?

                    Thanks

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                    • #11
                      Re: 1997 Evinrude 9.9, Loss of Power after about half throttle.

                      Even if the carb looks clean, all it takes is a tiny bit of crud in a jet to make it behave like that. Get a kit and do a full rebuild. Remove, soak and blow out all the jets.

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                      • #12
                        Re: 1997 Evinrude 9.9, Loss of Power after about half throttle.

                        Are both spark plugs firing? It could very well be that you are only running on one cylinder.
                        Author of LeeRoy's Ramblings http://www.leeroysramblings.com/

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                        • #13
                          Re: 1997 Evinrude 9.9, Loss of Power after about half throttle.

                          Thanks iwombat, I have a kit on the way. So my spraying fuel into the carb with no result was not an indicator that the problem is not fuel related? I believe the only needle valve on this carb is on the top plastic part. I'm assuming I should not clean the plastic part with carb cleaner? If the kit comes with a friction plug will I be able to remove the vertical brass tube for thorough cleaning?

                          Thanks machinist, It is firing on both cylinders. It will fire right up and idle beautifully with either plug wire removed! I can see how this could easily be missed.

                          I really appreciate the help here. Thank you!

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                          • #14
                            Re: 1997 Evinrude 9.9, Loss of Power after about half throttle.

                            Ak...can you post a model no.?...2 stroke?..4 stroke?...I've looked at diagrams at ********** and at shop.evinrude.com...hard to tell what links the throttle plate opening to the timing advance <link/sync>...I agree with you and would use only hot/soapy water on that plastic upper..be wary of removong that brass tube , I'd suggest you clean it in place....often times a small air leak at one of the fuel line connections can cause that "fluctuation" of rpms with throttle increase..does pumping the primer blub from the tank to the motor help when the motor is doing this above 1/2 throttle?

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                            • #15
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                              Re: 1997 Evinrude 9.9, Loss of Power after about half throttle.

                              Thanks ALTn it is model # E10REUS a 2 stroke. This motor is like new.

                              It appears to me that the timing advance is turned directly (as a whole unit under the flywheel) by the throttle linkage which in turn operates the carb throttle opening via a wedged shaped piece of plastic linked to a plastic roller on the carb linkage. If that makes any sense! My terminology isn't up to par.

                              I'm almost certain there are no air leaks. Pumping does absolutely nothing. I tore the carburetor apart and cleaned it with carb cleaner (metal parts) soaking for about 3 hours, poked out all orifices with thin strand copper wire and blew everything out with air. Yesterday I tried squirting a little gas in the carb throat while above 1/2 throttle with no response either, which is making me think it may not be a fuel issue.

                              I do have the carb soaking again as we speak, this time I'll let it soak for 24 hours. After this I guess I start "throwing parts" at it!

                              Thanks

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