ouboard not pushing boat at high rpm...

[birdleg81]

I have a 9.9 or a 15 HP mariner I just took out today. Runs good till like after half throttle then seems it revs without a load and stops pushing the boat. Doesn't seem to slip out of gear or anything. The bushing in middle of prop seems ok by looking at it. Anyone have any advice on the issue. The engine runs like a top till wot then just sounds like it gna explode... thx bird

 

[wifisher]

Re: ouboard not pushing boat at high rpm...

The prop bushing may be slipping even if it looks OK. Do you have a spare prop to try?

 

[birdleg81]

Re: ouboard not pushing boat at high rpm...

no spares, only had boat bout a week ish. this may sound dumb but I stood on prop and I couldn't get it to slip a bit and I'm 240lbs..

 

[Barnacle_Bill]

Re: ouboard not pushing boat at high rpm...

That certainly sounds like a spun prop. A prop shop can fix that like new for you cheaper than a new prop. You can verify a spun hub by putting adjacent marks on the inner and outer hub. Then try it again and see if the marks are still lines up.

 

[wifisher]

Re: ouboard not pushing boat at high rpm...

Could have a clutch problem if the prop is good. I would get a spare prop and try it first. I always like to have a spare prop with me anyway. You never know when you will hit something and trash the prop. Once you know that the prop is OK the clutch is the only other part that is able to "slip"

 

[birdleg81]

Re: ouboard not pushing boat at high rpm...

I took the bottom apart the nite I bought it, everything looked good. Not any wear on parts. I'm thinking prop is the issue. I'll mark it as stated and check it. Unless there other clutches? I havent checked out a diagram yet. Thx doe the fast replies

 

[birdleg81]

Re: ouboard not pushing boat at high rpm...

Well the prop is spinning on the bushing. Guess ill fix that and get back with yall.thx the help.... bird

 

[acarver81]

Re: ouboard not pushing boat at high rpm...

I am having a similar problem with my '88 9.9 merc. I took it out this afternoon and it ran great at full throttle for about five minutes, then it just stopped pushing the boat and the RPMs went way up before I could throttle it back. From that point on It would only move the boat at half throttle or less. Is that what yours was doing? and how can you check to see if the prop isnt seated right? Will it just spin on the shaft by hand?

 

[westjr8]

Re: ouboard not pushing boat at high rpm...

It could be a spun prop. But the part that worries me is when you said when you had it at WOT is sounded like the engine was going to explode. Have you run a compression test on the engine?

 

[birdleg81]

Re: ouboard not pushing boat at high rpm...

West... it was the prop on mine. Runs fine now. Acarver... as instructed to me I took white out marked a like on prop and down to the nut. Run it till it have the issues, if the marks don't line up, u need a new bushing( assuming u have one).. I just ordered a bushing a.d pressed it in. Runs like a new one now. You don't hear any clanking when this happens do you?