496mag HO “very sluggish power” ????

[282Captain]

Here at year end, running the boat prior to winterization, my port 496mag HO is drastically under performing and very sluggish. Half power. More throttle does not produce more power. It’s extremely “fat” or sluggish starting off trying to get on plane.

Thoughts???

[MNStCroix]

Bad gas? Years ago I accidentally put some in that had ethanol blended in and my engine ran sluggish like you described. Had to get it pumped dry.

[bruceb58]

Bad gas? Years ago I accidentally put some in that had ethanol blended in and my engine ran sluggish like you described. Had to get it pumped dry.

He has twins so bad gas should affect both engines equally.

[Whippled263]

What year in the engine? There is a Merc bulletin in regards to cool fuel system. Look it up and read about it. Basically the paint from inside the module delaminates and clogs the fuel injectors. This happened to my Powerquest with a 2005 496 mag. I had the exact same symtoms.

[bruceb58]

What year in the engine? There is a Merc bulletin in regards to cool fuel system. Look it up and read about it. Basically the paint from inside the module delaminates and clogs the fuel injectors. This happened to my Powerquest with a 2005 496 mag. I had the exact same symtoms.

On the same line of thinking, a fuel pressure check should be performed.