150 Mercury Black Max O/B motor problem.

[Ramon H. Paniagua]

I just bought a used boat with a Mercury 150 Black Max and as it goes past 4000 RPMs, the motor immediately goes into neutral. Anyone has any ideas as to what the problem is? Or with similar problems? Ramon H. Paniagua

 

[ibnfshn]

I doubt it is really going into neutral. You most likely have a spun prop. You can check this by using a magic marker and put adjacent marks on the inner and outer hubs. Then try it again. If the marks are no longer lined up as you put them then the prop is spun. This can be repaired by a prop shop.

 

[Docksidemarineservices]

What condition is your prop in. Possible cavitation.

 

[fastjeff]

Spun hub! You can verify this by making a mark on the inner and outer prop hubs, then taking her for a ride. If the marks moved, there's your answer.

Jeff

 

[Ramon H. Paniagua]

Thank you all for your input. I am going to try the suggestions and hopefully I'll get to the root of the problem. Ramon H.Paniagua