225efi problem???

[bobby]

I have a 2002 Mercury 225efi, took it out for the first time this year this past weekend. Motor ran great all day, when i was coming in I let her eat for about one mile then backed it down to 4,000 rpm's for about another mile till i got to the no wake zone. Idled for about 1/2 mile, noticed the motor was running a little rough after I idled this distance. Went to get up on plane and the motor was very slow responding. Put it on the trailer and pulled the plugs, one of the plugs is black and wet (fouled). What would cause this and will just replacing the plugs be ok? Plugs have been in motor for about 1 1/2 years, and all fuel lines have been replaced. Thanks

[bassman34]

Fresh plugs deffinatly will not hurt a thing. Lot of variables here too, how was the boat winterized? Was the gas fresh? If not was it treated with a stabilizer?

[EuropeanAM]

There are numerous possible causes.... failed/fouled spark plug (you're overdue, BTW), reeds, ignition problems, leaking fuel pump diaphrams, flooding VST, flooding injectors, etc.

The obvious starting point would be to replace your spark plugs. Standard production 3L EFI models require that you use ONLY Champion QL77CC spark plugs.