Seafoam does work but caution is needed if the entire fuel system is dirty.
Used it in a '96 SeaDoo that I got used. It loosened up the green algae in the fuel system and plugged the little filters in the Mikuni BN carb inlets on it. No fun idling back to the dock.
What a PITA to pull those carbs and clean them.
Tank dirty, pull and flush everything for a once and done. Carb dirty, pull it and clean. ''Mechanic in a can'' has its pros and cons.
Stabilize your fuel cans when you fill the cans, I call it ''self-proofing''.
Marine grade stabilizers are all I use in all my equipment.