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Mercury 9.9 Issue

jcountry

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The Hen that laid the Golden Legos
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Hi

I have a mercury 9.9 that 'slips' sometimes.

It only happens after I have been running for a while.

When i go to idle or low throttle, and then wind back up toward full power, it is like the engine power rolls back to almost nothing. (Engine rpm pretty much goes all the way back to high, but not quite. )

Feels like a slipping clutch in a manual transmission car.

I often take the boat to Juliette, and usually a couple strands of that grass stuff get caught in the prop, but I'm not sure that's related, because this issue only started recently, but I have taken boat there for years.

Any idea what's wrong (the BassPro shop was entirely useless in troubleshooting this. They told me "bad plugs," but I know enough about engines to know that's complete BS-especially when I changed to exact OEM plugs at least 15 hours of run time before this started happening and never saw the first hiccup.)
 
Heat makes it slip more. The hub is a cushioning device for the gear train. When cold the rubber holds a little better.

 
I just checked out a video on spun hubs.

I think you guys cracked the case!

Thanks, fellas! Y'all rock!!

BTW-I'm even more pissed at the Bass Pro engine shop now. After keeping the damned thing for two weeks, this is something they could easily have checked.
 
I'm checking out the parts schematic, and it looks like the hub may be built into the prop on this 9.9.

I don't see a separate hub like in the videos.

Anyone know whether this is the case?
 
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