MERCURY 60HP BIGFOOT ENGINE REVVING TO 6000RPM LIKE IT GOES TO NEUTRAL

[fiel19631oz]

When at full throttle pontoon boat acts like propeller is out of water and revs to 6000rpm. This mainly happens in choppy water. It makes a different sound before this happens. Prop and bushing was changed and it ran worse. Reinstalled old prop and it does good until you run wide open for 15 minutes and then makes noise/vibrates and just like you put it in neutral and revs wide open. Ease back on throttle and it will take back off no problem for 15 minutes. 2000 mercury 60hp bigfoot 2 stroke engine. Would a bad neutral safety switch do this? Does it have one?

 

[GA_Boater]

Howdy.

Neutral switch only allows the starter to work in neutral. After the motor is started, the switch can be thrown overboard with no ill effect. That is until you try to start the motor again.

This sounds more like a motor mounted too high or a spun prop hub.

Draw a line across the hub and prop. Look at the line after the next over-rev. The hub is spun if the line is no longer straight.