2002 F100 is "hunting"

[YamF1002000]

Hi Guys,

I am from South Africa. I have a 2000 Yamaha F100 (bought in 2002 but plate on motor shows 2000 model?) which starts and runs like a dream, that is except for when it is running between 4200 - 5000 rpm.

At these RPM's it sounds as if the motor switches between more and less cylinders running with the associated power loss (It is the best way I can describe it). A friend told me the motor is "hunting"..??

What can be the cause and how do I fix it? Can it be sucking air? The motor has done 188 hours.

Is it common for these motors to leak oil? there is oil on my boat transom, dripping down at the back of the boat.

Thx Yam

[rodbolt17]

there were some oil pump issues about that year range.
in the US it was covered by a tech bullitin and Yamaha.
its possible the fuel pump is failing or the carbs need cleaning.

[YamF1002000]

Thanks Rodbolt17.

I'll have it checked.