1987 Yamaha 9.9: Where is the Idle Fuel Mixture screw? (pic)

[ST]

I read sometimes ago at this forum that if your engine seems to wanna quit if you increase the RPM, but picks up the RPM when you partially closed the air inlet opening with your tumb, this indicates that the engine is lacking fuel. When the engine gets hot however, this problem seems to go away.<br />That's is what's happening to mine, so I intend to make the fuel mix richer, but can't find where the screw is in the carb. Would someone(s) help point me in the right direction please, here's the carb's diagram; thanks!<br />

]http://www.boats.net/yamaha/partsystem/browse-model-parts.pl?type=component&*******=cef029d16ac7cd19611648c07985e645&catalog=Outboard&year=1987&model=FT9.9ELH&component=376100[/img ][/URL]<br /><br />031006 19:19 PST url edited...st.

 

[WillyBWright]

Re: 1987 Yamaha 9.9: Where is the Idle Fuel Mixture screw? (pic)

#13. Turn it clockwise for less fuel, ccw for more fuel. I'd try 1/8 turn ccw. More if necessary 1/8 at a time. It should chug slightly. Don't adjust for the smoothest or the fastest idle running characteristics. It needs more fuel than that for acceleration. Roughly 1/4 ccw from smooth and fast.

 

[ST]

Re: 1987 Yamaha 9.9: Where is the Idle Fuel Mixture screw? (pic)

Hi Willy,<br />Thanks for taking the time to respond and gave valueble pointers. I've just tried and played with it per your directions, but before I am done, the wife showed up and warned me it's "too early"-neighbors (08:00AM in Calif.)- oh well; I'll continue a little later...But thanks again!

 

[ST]

Re: 1987 Yamaha 9.9: Where is the Idle Fuel Mixture screw? (pic)

I continued tuning up the carb today, tweeking with screw no. 13 as indicated by the drawing above, and seems to be able to rev up the engine to a higher RPM without much hesitation, even though I feel it's not perfectly smooth. Perhaps, cleaning the carb (again) is next...thanks Willy!

 

[Silvertip]

Re: 1987 Yamaha 9.9: Where is the Idle Fuel Mixture screw? (pic)

If you are making this adjustment in your driveway using muffs, you will likely have to readjust it when the boat is launched. There is no back pressure on muffs so when the motor is dunked the increased back pressure changes the engines idle mixture requirements. If you can run it in a barrel that would be better.

 

[ST]

Re: 1987 Yamaha 9.9: Where is the Idle Fuel Mixture screw? (pic)

Upinsmoke,<br />Thanks for your input! Ok, I'll play again with the adjustment as soon as I get a change to launch this; hopefully soon....!