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Throttle problems on CT99C

F

fatbear

Contributing Member
"My outboard idles fine and re

"My outboard idles fine and revs up fine, but it has trouble running just above idle. The problem appears to be in the linkage. I think I might have figured it out but I have no experience with outboards and I would really like to see a confirmation or rejection of my hypothesis before I go buying parts and tearing the thing apart.

Please look at this photo: http://myflotsam.com/Images/SuzukiThrottleQuestion-1.jpg". I apologize for the mis-focus, but it will suffice.

The numbers point to:
1) notch in plastic part
2) plastic cam-like part that moves with the throttle.
3) starter rope housing (just for orientation.)
4) roller pin, part of linkage to carburator.
5) air intake (just for orientation.)

The throttle moves the "cam-like plastic part" (2) which gradually pushes outward on the roller pin (4) and advances the throttle. Or that's how I think it is supposed to work. What actually happens is that you turn the handle and turn it some more and suddenly the engine jumps up from idle to a moderately high speed. From there it advances smoothly. Slowing down, you drop suddenly to idle. Worst of all is maneuvering in the marina because it is almost impossible to maintain a power level just slightly above idle.

I suspect that the notch (1) is from wear and is not supposed to be there. Am I right? If so, does anyone know what this part is called so I can buy another one? If I am wrong, can anyone explain how this is supposed to work so I can figure out why my motor is misbehaving?

Thank you,

FatBear"
 
"I have been looking for this

"I have been looking for this part online and cannot even find it. Even the sites that have a lot of parts do not seem to have linkage parts, cables, etc. Where would I find this part if I do need to replace it?

Thanks."
 
"I did find the part shown and

"I did find the part shown and listed in the Suzuki catalog at brownspoint.com. It is the throttle cam. But the illustration is from an angle which does not show the shape of the cam very well. It appears to have a bump in this location, but not such a deep notch. Does anyone out there have a DT9.9? You can see the throttle cam simply by removing the engine cover and advancing the throttle from the hand-grip (you don't even have to get your fingers dirty.)

Meanwhile, it also appears that this part is obsolete. Any idea where I might still find one?

Or is there a similar, newer part which would bolt on, but maybe has a different cam profile. If so, I could file it to work for me...

Thanks"
 
Your diagnosis sounds good to

Your diagnosis sounds good to me is it possible to simply bolt a small piece of sheet metal onto the existing throttle cam and to file/cut it to make an even profile.
Alternatively just file the throttle cam its self to remove the lump created by the missing piece and create a smooth profile. You will probably have to adjust the min revs after doing this but then it should run fine.
 
"Hmm, interesting idea. I wil

"Hmm, interesting idea. I will certainly hang on to it in case I cannot get a new cam. I would probably use aluminum because it's easy to shape and wouldn't wear out the roller that rides on the cam. As the throttle is advanced it pushes against the roller, causing the roller and its shaft to tilt. I'll have to make sure there is enough room on the roller to accommodate the higher cam, but it just might work.

I thought about filing the cam itself, but there would still be a steepness right in the range I want to run it at. Not as steep as now! But maybe still too steep to be practical maneuvering around the marina.

Thanks for the backup plan."
 
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