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Muskie Fishing -> Muskie Boats and Motors -> 9.9 4 stroke issues
 
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Message Subject: 9.9 4 stroke issues
Fisher
Posted 11/5/2018 7:44 AM (#922622)
Subject: 9.9 4 stroke issues





Posts: 425


Location: Roseau
It sputters out at half throttle and the plugs are black and wet, oily.
Main cause?
Fixable?
Thanks
genesisperformance
Posted 11/5/2018 10:17 AM (#922645 - in reply to #922622)
Subject: Re: 9.9 4 stroke issues





Posts: 403


Location: Lakeville, MN
Probably plugged or dirty jets. Mine gets bad if i dont fire it up once and a while.
North of 8
Posted 11/5/2018 11:14 AM (#922652 - in reply to #922645)
Subject: Re: 9.9 4 stroke issues




I had a similar problem with my Suzuki 4stroke kicker. Ran fine at low speeds but as soon as I gave it half throttle or more it would run awful. Dealer took the carb apart, cleaned the jets and it runs fine. He did say that if all I use it for is trolling at lower rpms, to open it up and run at full throttle for a few minutes on a regular basis. Had it done in the spring, still running great.
VMS
Posted 11/5/2018 11:42 AM (#922659 - in reply to #922622)
Subject: Re: 9.9 4 stroke issues





Posts: 3469


Location: Elk River, Minnesota
Hiya,

This could be two distinct things. First, it might just be an adjustment of a slow speed needle. On older 2 stroke motors, you could adjust the lean/rich mixture to get the burn correctly. This was due to differences in altitude use and could be done by the user. If your motor has this capability (sometimes you need to use a screw driver to adjust it) it might only need that needle adjusted. It is usually located on the front of the carb above the butterfly.

If you have not used the motor much or this adjustment needle is not accessible (newer motors this is a factory set item and is not accessible) it is more likely to be a stuck float needle allowing too much fuel to enter the carb, creating a rich situation. It's caused by the same issues as clogged jets, except it is an excess of fuel rather than starving for fuel, which is what clogged jets would cause.

The last possible cause could be spark plug wires that are old and have too much resistance in the line. My gut instinct says this would not be the case as this would affect idle as well....

I'm thinking carb rebuild as well.

If you are in the twin cities area, we could do it in my garage...save you a few bucks rather than pay a dealer service fee...

Steve

Regardless, a carb rebuild is in order and if you are handy enough....it's a DYI job.
North of 8
Posted 11/5/2018 12:06 PM (#922660 - in reply to #922659)
Subject: Re: 9.9 4 stroke issues




When I posted my motor's symptoms last winter, VMS did a preliminary diagnosis and that turned to be the problem. Not sure I ever gave proper credit. Soon as snow melted and I could get my boat to a dealer, I did and what VMS thought was the problem was indeed the issue.

Edited by North of 8 11/5/2018 12:08 PM
Fisher
Posted 11/5/2018 1:46 PM (#922667 - in reply to #922622)
Subject: RE: 9.9 4 stroke issues





Posts: 425


Location: Roseau
Thanks for the info, will start with that.
This motor is the one with an automatic choke.
Not sure if that could cause issues also?
Thanks
VMS
Posted 11/5/2018 6:22 PM (#922713 - in reply to #922622)
Subject: Re: 9.9 4 stroke issues





Posts: 3469


Location: Elk River, Minnesota
Hiya,

I would think it is doubtful to be the choke as the motor would then sputter at idle pretty bad as well... Definitely something to consider, but the symptoms you describe would not lend to that being the issue...

North...Thank you for the kind words my friend!!

Steve
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