1994 Yamaha 85Hp 2 stroke issues!

[xhunter911]

I recently bought a used boat with the 85Hp yamaha engine on it, and for a couple weeks now it has been running top notch! The boat has a built in gas tank which I am only familiar with portable tanks and have never fueled up this way before... The original owner of the boat said he only used yamalube 2 stroke oil so I continued using what he was running in the engine and with a oil ratio of 50:1, but yesterday I was unable to purchase it from a local marina so I tried a different brand 2 stroke oil... I already had a half a tank of gas butr I wanted to add 12 more gallons just to be sure, I poured the oil in the gas tank ran it to the fuel dock and proceeded to fuel up! I left the fuel dock and the engine seemed to run just as good as any other morning at a slow speed idle for about 1 mile, then when I opened it up it ran great for about two minutes and then all of a sudden rpm's dropped and it lost all power and came to a hault... The engine did not shut off, but when I put it back in forward it sputtered and continues to run like crap, and ocasionally shut off! When I engage into forward, I can throttle up and nothing is there, unless you throttle very slow the engine will slowly go back to normal, but only for less than a minute or so.... I replaced the plugs they were sorta wet with oil, and also changed the two fuel lines from the external fuel filter and the squeeze ball line to the engine!!! What is going on here with this engine... Any suggestions, answers?????? PLEASE HELP

 

[xhunter911]

Re: 1994 Yamaha 85Hp 2 stroke issues!

I just wanted to add a few other things that I remembered about yesterdays troubles! After I changed the plugs and the fuel lines, which took about an hour from running back and forth from the store...
We decided to fire up the boat and head out a couple miles and drift for flounder which the boat seemed to run ok again for that short period of time... A few times I had a little power loss, but I was able to correct that by cutting the throttle back a little.... We shut the engine down and drifted for over three hours, and decided to start in... The engine fired right up and ran as if there was no problems at all... We were doing a little over 30mph for 1.6 miles until the problem started again with the powerloss and sputtering!!!!!
After reading several things in my repair manual it looks like the problems all started because of the way I mixed the oil into the gas tank... I poured the oil in without adding gas at the same time... Does this sound right?????

 

[CrappieLimit]

Re: 1994 Yamaha 85Hp 2 stroke issues!

I just bought a 1993 Skeeter SS90 with a Yamaha 85HP motor. The other thing to look at is if the fuel from the dock was bad. Look on the left side of the motor. There is a glass fuel filter that will indicate whether you have water in the fuel.
Good luck

Grant