1989 Yamaha Pro50LF loss of power and running rough

SteveNix

Seaman
Joined
Jan 23, 2006
Messages
67
1989 Yamaha 50HP long shaft.
Motor has run very strong for past 3 years.
Took it out the other day. Had a very hard time starting. Cranked on and off for probably 5 min trying to get it running.

Once it started and warmed up took off to our favorite fishing hole approx 2 minutes away. Motor ran fine. Lots of power as always.

Started up again fine. Took off and planned out, when motor began to loose power and sputter and run rough.
Lowered my RPM and it began to run fine again.
Again, up on plane, and within 10 seconds power was lost again. Back to idle and it ran fine.

Thought maybe it was missfiring, but as i removed each spark plug wire, the motor ran differently with each one, so i wasnt able to pinpoint which cylinder was the problem.

Here is a link to my youtube video of what its doing.

http://youtu.be/ojTMLisLPhs

any thoughts?

Thanks
 
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