femmepologrl

I have a 2001 Challenger 2000 jetboat with a merc 240. At idle and up until about half power, everything seems fine. At half throttle, the engine bogs out, then tachs out, and the boat goes no where. Has this happened to anyone?
Thanks

I have a 2000 challenger, this happened to me last weekend. After having it checked, they told me that one piston was getting ull power and not the other. Somewhere there is a clog or something and this is a mercury only part allegedly, 8500 to replace it. I am at a loss at the moment, the boat is only worth 10k. If you get an answer please email me femmepologrl@aol.com. Need the answer too. Thanks Lin