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NJfishinGuy

HELP! please help me diagnose this outboard problem!

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ok 99 mercury 60hp 2stoke oil injected. the motor i has about 30-40hrs on it. was set up for storage a couple years ago and was a dry tank.

anyway i get on the water and after idling out of the no wake zone i get on it but after about 1 min of running fast the engine just looses rpms and come downs to about 2k rpm and stays around 8mph even with the throttle wide open.     sometimes itll just pick up and take off all on its own if i keep the throttle down and then loose rpms on its own again shortly after.

sometimes it just wont get up and move fast for a while or itll run great for a while its very random. also noticed when it acted up if i let it idle, once in a while itll stall and when i try and start it, it gets flooded.   itll blow a bunch of smoke and smell like gas but  it clears out pretty easy .

when the motor isnt acting up its runs amazing. not quite sure where to start and i really hope someone has a recommendation. hopefully this explanation is understandable lol

i changed the plugs and checked the fuel filter already. this is also running on all fresh gas

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Just a shot in the dark, but maybe a safety type governing device malfunctioning.  I would think you need electronic analysis by a Merc certified mechanic.  Or maybe a safety type governor acting correctly in which case you have something more wrong on your hands.

On an older motor I would assume it is intermittently missing a cylinder and trouble shoot the ignition.  Starting by removing a spark plug wire while the motor is running to see if it affects the performance.  If no change in performance with the wire off then that cylinder is not firing for some reason.  Check each cylinder.  

good luck.

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Is your vent open on your fuel tank? Almost sounds like a slow venting, or vapor lock problem. Try unscrewing your fuel cap to let it vent next time it acts up. If you vent the cap and the RPM's come back up then you know your creating a vacum in the tank not allowing the fuel to flow properly.

Could also be a gov problem as someone stated, but lets start easy and cheap and go from there.

Bill

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When you drain the fuel tank you don't drain the needle and seats in the carbs. They are sticking and need to be cleaned and new gaskets installed. While your in the carbs go ahead and change the floats to allow you to run the 10% ethanol gas mixture. We ran some in my son's boat and had to rebuild all three. The older floats were not compatable with the new fuels out there. Changed them out and no problems since.

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