1996 Yamaha SSII Fuel

Den, I've never used Seafoam, but the startron additive isn't really a "cleaner" so to speak.....the enzyme is designed to help keep the ethanol and gas mixture homogeneous and stay "fresh"...it won't clean up any residue in the carbs, its more for prevention of gum buildup. The problem comes more from the tank itself. prior to ethanol, the MTBE gas left a bit of a residue in the tank that was no big deal, but when the ethanol came aboard, it acted as a solvent and started to clean your tank...that stuff which looks like little orange gels is the residue causing the problems to many boaters, myself included. After rebuilding carbs I ended up buying new ones. They ran great for one season and now are acting up again...I pulled the tanks for inspection and possible cleaning and noticed some severe pitting so they are being replaced and hopefully end this nightmare. The Grady dealer has told me too much of an additive is not good for the engines....I would heed that warning....you may need to pull the carbs off and try again. Soaking is OK, but the best way to clean them is in an ultrasonic tank. It will dislodge anything stuck in a passage that normal soaking will never get at...I would also check your fuel system and filters to see where the junk is coming from. Otherwise, it will come back.