01 Johnson Ocean Pro Vibration Problem

This problem just began last night with no previous warning(s). The motor starts and idles with no problem but when it gets to about 3000rpm an incredible vibration starts and the tach. continues to increase without the throttle being touched. The boat doesn't actually go faster, only the throttle steadily increases. The results are identical in neutral or in gear. The motor also makes a pretty terrible sound when the vibration begins, kind of a rapid knocking sound.

Any help appreciated!

Re: 01 Johnson Ocean Pro Vibration Problem

hopefully it is a spun prop. mark your prop.

Re: 01 Johnson Ocean Pro Vibration Problem

After researching other areas of the forum, the problem really sounded like a SLOW issue, but it no longer exhibits these symptoms. Tonight, I started the motor and let it idle until it reached normal temperature. I then throttled up to about 30000rpm (in neutral) and the problems start. The throttle continues to accelerate on it's own until about 4200rpm and then it will bounce back to about 3000rpm. This cycle continues without touching the throttle. It sounds pretty raggedy and will bounce between 3000rpm and 4200rpm, occasionally a little higher.

Is this a fuel or throttle situation? It starts and runs perfectly until about the 3000rpm level.

Re: 01 Johnson Ocean Pro Vibration Problem

Diagnosing an engine over reving in nutral is impossible. Dont rev over 1200 RMS in neutral or the enging may run away and explode....

Re: 01 Johnson Ocean Pro Vibration Problem

RPM increase with no increase in speed or throttle input does sound like spun prop, put it in the water, mark the hub as Tash said and give it a run then check to see if the hub slipped.

SLOW doesn't increase engine speed, it makes it go SLOW .....doh!
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