40 HP Yamaha loss of power fixed

My 40HP 3 cylinder purchased new in 1996 lost power and seemed to be running on 2 cylinders. Pumping the primer bulb made no difference.
I pulled each float bowl drain and found only a few drops in the lower carb.
I pulled the fuel feed line to the carb and pumped the primer and had good flow.
Pulled the carbs and found the bowls were clean as I have allways drained them for storage. Did a complete cleaning and took it out for a test.
It ran for 30 seconds WOT and lost the bottom cylinder but it would cut in and out.
I replaced the float needles and seats and it has been fine.
The replacements have an 01 in place of the original 00 in the part number indicating a change. The color of the rubber tip on the needle is black and the original was red.
I wonder if the original material was not compatable with the 10% ethenol we have in Maine?
If you do this be prepared for sticker shock.
Cost of 3 each needles, seats, o rings and clips $ 92 from Yamaha.

Re: 40 HP Yamaha loss of power fixed

could be the ethanol working on those needles/seats. I use the Stabil Marine, Yamaha Ringfree and a fuel/water seperator to help with this ethanol issue. With the cost of Yamaha parts and repair headaches, the preventive maintenance has to be the best and most cost effective way to go. when you drain the carb float bowls and before you replace the drain plugs, pump the bulb a few times to open the float needles, then they will be stored in the "open" position...maybe better for the seats. Good Luck!

Re: 40 HP Yamaha loss of power fixed

robert graham said:

could be the ethanol working on those needles/seats. I use the Stabil Marine, Yamaha Ringfree and a fuel/water seperator to help with this ethanol issue. With the cost of Yamaha parts and repair headaches, the preventive maintenance has to be the best and most cost effective way to go. when you drain the carb float bowls and before you replace the drain plugs, pump the bulb a few times to open the float needles, then they will be stored in the "open" position...maybe better for the seats. Good Luck!

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Thanks for your input.
Back in 1996 when I rigged the engine I also installed a Racor 2 micron water separator filter as the Yamaha unit did not impress me.
I have also used Yamaha ring free and stabil.
I will try running the fuel out of the carbs after each use.
Corvette327