2007 Mercury Optimax 90 DFI - Intermittent Loss of Power

Rosico

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Feb 16, 2015
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Last summer my engine started acting up. I would be at full throttle and all of a sudden I could feel the engine HP drop and I would slowly fall off of a plane. The engine sounds fine, no smoking or shudders and I still have some power but not enough to get on a plane. Sometimes the HP will drop off and come back a few seconds later, other times I would throttle up and down, turn the engine off and on, and then it would come back a few minutes later. Towards the end of the season it got stuck in this state of low power, and I plowed water back to the boat launch. I changed the fuel filter, spark plugs, and air filter, I took the boat back on the water and it was running great for about 5 minutes and then I lost HP again for about 30 seconds and then I was back to full speed and I ran the boat around for about another 10 minutes with no issues. I am at a loss and need help. I dont believe it's a fuel issue, this has persisted for a couple tanks of gas. I have been running ethenol free for the last 2 years.
 
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