by chaz
(maricopa az)
My johns evinrude 120 v 1988 runs great around 4000, but each time I ran the engine up to 5000 for any length of time, it lost power and I had to drop it back to idle or a little above. Then when I tried to throttle up again, tremendous vibration set in, and no power. After running at 1500-2000 for a while, I could throttle back up smoothly and run continuously at 4000, no problem. However, each time I ran up to 4500 or above the same scenario would play out.
Anyone know what is going on here?