Yamaha 85hp - loss off power

Hi,

I have read most post on loss of power but this has not helped me much in resolving my issue : (

I bought a used boat with a Yamaha 85 hp, it was working perfectly for 6 to 8 months, but one day I the engine started to have slow reaction when increasing power from the control ( especially in the beginning of the trip) although I do run the engine for 5-7 min before..

In a month's time the max power became at 2/3 of the Control any thing after that did not give me increased power. I have lost around 10 to 15kt of the engine out put. When the control is fully opened the engine dos the same.

I did find out that my Oil/petrol ratio was wrong and have corrected it. I have done the following:

Cleand the carbs
Replaced the fuel pump
Replaced the water pump
new spark plugs
cylinder compression test ca 100 on all 3 cylinder
Opend and inspected all internal fuel lines (all were nice and clean)
New fuel filter
New female fuel line connector at engine side.
New fuel tank
Had e mechanic to check my electrical wires and said it's all fine!!

Please help : (

So what was the issue with the oil / fuel ratio ??------Do you have spark at each cylinder that jumps a gap of 3/8" or better ?--------Are all 3 carburetors opening up ?----------When the motor is at full throttle on the water / lake , look into each carburetor with a strong flashlight.---See if the same amount of fuel is coming up each nozzle.

Does the boat live on the water or on a trailer?

aliboy- the boat lives in the water, i have cleaned and painted the bottom of the paint 4 months back. I checked the boat when the boat was clean and still the same issue.



racerone - I was adding to much oil to the fuel 1:35, now i'm on the right ratio 1:50. how do I check the Spark 3/8" ??

I have not checked the carb nozzels while running, I will check on Friday and let you know