'89 Yamaha 9.9 Four stroke - stalls unless high throttle

[MQMurphy]

I searched back a ways through the posts, didn't see any that address this -
my '89 just had a recent impeller and thermostat replacement. On the recommendation of the service shop I added a bottle of 'Ring Free' to the fuel tank. First day running for about an hour the engine started to stall out unless it was revving high. Are these things connected? Ran pretty well before that. Idled nice and low. Is there an adjustment I need to make on the carb? Service guy told me old Yam 4 stroke carbs are complicated, which probably puts that job (rebuild) beyond me. Can't afford to put the motor back in the shop, though. Any suggestions?

 

[sdsaw]

Re: '89 Yamaha 9.9 Four stroke - stalls unless high throttle

Carb is not complicated.
You have an adjustment for the idle mixture on the top of the carb. It's a slotted screw surrounded with a black rubber ring. My manual says to turn clockwise till it LIGHTLY seats then back out 3 turns +or- 1 turn.
You also have an idle speed adjustment. Adjust by ear.

If this doesn't help, you probably have a clogged jet or passage which easy to clean with some carb cleaner and compressed air once you remove the carb from the motor.
If you have the carb with the auto-choke don't let the vacuum lines scare you, just label them as you remove them. You probably won't have to touch these to clean the carb.
A genuine factory service manual shows clearly how to do all of this.
The one that I use has the # LIT-18616-FT-99. Well worth the money.

Good luck and post back if you have any more questions, Scott

 

[MQMurphy]

Re: '89 Yamaha 9.9 Four stroke - stalls unless high throttle

Thanks for the tips, Scott. I'll try those things out this weekend and let you know how it goes.
Mike