At Full Throttle , boat won't move. 9.5 hp Johnson

[brianwrites]

I was out on the lake and my jon boat slowed to a halt. Shut it down then started her again. Went from idle to full throttle and the boat wouldn't move. Seemed as though the propeller was not turning. I looked in the water I could the propellar was barely spinning when I increased the throttle. Took the prop off at home and the pin was still in tact. Any advice? Is this the dreaded impeller replacement? THanks in advance.

 

[racerone]

Re: At Full Throttle , boat won't move. 9.5 hp Johnson

What do you mean by " dreaded impeller replacement " on this motor.-------Have you looked at condition of the gear oil ?-----It could be a spun hub inside the prop.----So try another prop first.

 

[SeaKaye12]

Re: At Full Throttle , boat won't move. 9.5 hp Johnson

Sounds like you have a spun prop. Look to see if the propeller has a rubber insert inside of it. That part can slip....even though it might appear OK when you have it in your hand.

With the prop off....turn the motor over with the rope...and see if the prop shaft turns forward and reverse in relation to the shift lever position. If it does....then the issue is in the prop itself.

Repair at a prop shop...or replace.

The impeller is the part that cools the engine....a rubber vaned pump right below the cavitation plate. Unrelated to your issue....but very important.