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Old 01-08-2023, 08:11   #1
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Boat: PDQ Classic 32+
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Yamaha 9.9 won't run at low rpm

Hello,

I have two 2021 Yamaha 9.9 high thrust motors that run off of a central fuel tank. This season one of them has been intermittently not running at low RPM's, if I start it and keep it revved it will run just fine.

I removed the carb and cleaned it and found nothing worrisome.
I don't believe it's bad gas because it's only one motor and we recently burned more than a tank of gas.
I increased the idle rpm's to 5-600, which helped for a short time and then it started again.

Thoughts?
John
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Old 01-08-2023, 08:28   #2
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Re: Yamaha 9.9 won't run at low rpm

Partially clogged pilot jet. It happens with ethanol fuel. Will likely also idle better at half choke.

I use Startron and stabil for ethenol at 'storage' mix ratio always. I also try to cut the fuel and idle the fuel bowl empty if it's going to sit for any length of time.

Remove the pilot and main and soak them in carb cleaner for 24 hrs, then blow them out with a can of carb cleaner and re-install.
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Old 01-08-2023, 08:31   #3
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Re: Yamaha 9.9 won't run at low rpm

Thanks, I also use Startron religiously, and I did clean the carb, all jets were clear. Will try the half-choke suggestion.
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