I have a 2004 mercury 90hp 4 stroke carburated. I recently purchased the boat from a marina and was told the engine was overhauled. I ran the boat 4 times this year has about 5 hours of use. On the last trip I started the engine and made it about 8-10 minutes on water at 4500 to 5000rpm before the alarm started beeping and power dropped to 3200rpm, no matter how much throttle I gave it. I checked the prop and was clean. I was able to crawl back across the lake to dock. I am not a mechanic is there a place to start looking without pulling boat out of the water and could be an easy fix??
