30hp hesitates at cruising RPM

[Waldguy]

My 1989 (or so) Yamaha outboard won't reach full throttle without hesitating. I've checked the fuel supply and it seems fine. When my 16 ft aluminum planes out, the engine will begin to hesitate if I increase the throttle to about 3/4. I only use about 3-4 tanks of fuel a year. I just gapped the plugs, and they didn't seem overly carboned up.
It idles all day long without a problem.
Is it due for a carb cleaning? Seafoam treatment? Thanks for any help.

 

[deejaycee_2000]

Re: 30hp hesitates at cruising RPM

Time for cleaning those carbs really good ... soak them in carb cleaner for 24hrs then blow out with comressed air ....

 

[Waldguy]

Re: 30hp hesitates at cruising RPM

Thanks for the advice.
I just took it out this week again, adding 1/2 can of Seafoam to a tank. It increased the speed obviously, but not all the way, pointing to carb problems.
I have some mechanical ability, but no experience with outboards. Should I buy a manual and attempt this?

 

[deejaycee_2000]

Re: 30hp hesitates at cruising RPM

it is always good to have a manual .... but to clean the carbs really good isn't that much of a big effort, get yourself carb cleaner, take them apart one at a time and soak overnight and then blow out with compressed air .... then put together and then do the next carb, so you don't mix the parts up with the other carbs by accident ...

 

[Waldguy]

Re: 30hp hesitates at cruising RPM

Well, rather than strip down the carbs, I did the lazy thing over winter. I mixed gas 1-1 with Seafoam and allowed the carbs to suck it down before turning off the motor.

I took the boat out yesterday and there was not a whiff of hesitation; it ran beautifully. That stuff works great.