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... you ask questions, then never listen to the guys that know why your motor sucks the cock. seriously man get a grip your motor needs good fuel filtration before the fuel gets to the motor. its just the way these yamaha's are.

I believe you can buy a sierra element for the merc base that is 10 micron and is shorter.

I would try pouring seafoam directly into the water/fuel separator filter on the motor and run it through and see if it helps. It might just clean out anything gunked up thru the motor including the injectors. Then run high test always just to keep the 'ethanol' out which melts rubber parts and causes havoc.

the only ethanol free gas available in our general area up here is Shell super. Not always available on the water.

Steve

so lets back track here Charlie. your yami was running great ,you changed your spark plugs sometime ago. you had a surging problem. you changed your filters . you had a leaking fuel tank. you found black contamination in your fuel system. then it was hard to start . now it runs on 3 cylinders. ( maybe not in this order ? )

1. so check to see if all cylinders have a good strong spark. if ok I would start from 0 and go through the fuel system again.
2. if 3 cylinders only have spark correct that problem.
3. otherwise at this point I would seriously consider. taking it to a experienced tech. maybe DOC and have it diagnosed correctly.
4. if you leave it over the winter and the injection system is contamined . a lot more severe damage may occur over the winter. I would fix this issue before you winterize the boat. piece of mind.

these are just my opinions. v8

X2 you dont want anything growing in your fuel system over the winter,,make sure everything is cleared and sea foam the snot out of it..