Outboard issues 2006 honda 40HP

A mate of mine has a Honda 40 HP four stroke outboard (2006) which used to run great but has developed an unsual problem. Under load on the way back in at about three quarter throttle the engine seemed to "Free rev" so he quickly backed it off to avoid damaging the outboard due to the over revving but once the throttle was backed off to neutral, the engine seemed to be fine and it was put back in gear but as the motor approached three quarter throttle the problem seemed to appear once again. So I guess to sum it up motor runs fine in idle, low revs etc but once it approaches three quarter throttle under load this problem seems to happen.

My mate limped the boat back in at low speed to avoid this problem but it has the two of us wondering what it may be so we were wondering if anyone has had any experiences like this with their motors?


Posts: 307

Date Joined: 01/09/09

over revving

Mon, 2012-10-15 20:38

My quick guess would be either cavitation or the prop ..

 

grantarctic1's picture

Posts: 2546

Date Joined: 03/03/11

Agree

Mon, 2012-10-15 20:49

Agree with fishfish, have had a simular problem. Cavitation from the prop wich led to the shaft getting damaged (seals etc ) . A dent in the prop started it all and my lack of getting it fixed cost a lot more in the end .

Posts: 457

Date Joined: 03/09/10

It could be cavitation

Tue, 2012-10-16 06:51

but it may be that the rubber bush in the prop letting go.

A common problem that occurs after a few sandbar encounters and gassing it up {outboard} out of the blocks from a standing start.

Posts: 198

Date Joined: 25/05/10

? Prop bush is stuffed and

Tue, 2012-10-16 06:46

? Prop bush is stuffed and fails or slips under high load.

tantrum's picture

Posts: 79

Date Joined: 09/06/12

come to think of it He was

Wed, 2012-10-17 02:23

come to think of it He was saying there was a small dent in the prop... Phil Sommerville the mobile boat mechanic is coming down to check it out for him so hopefully for my mate it's not too costly.

carnarvonite's picture

Posts: 8673

Date Joined: 24/07/07

Prop

Wed, 2012-10-17 08:16

Agree with the others, defintitely a prop problem , either cavitation or the rubber letting go.

jr_frosty's picture

Posts: 10

Date Joined: 12/07/12

prop

Wed, 2012-10-17 21:14

 Spun prop bush for sure. needs new prop

 
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