There are any number of reasons to polish your fuel, including if your boat has not been used in awhile, discovering the fuel cap was loose and water may have gotten in, the boat is new-to-you, you suspect bad fuel or you know you will be headed off into lumpy conditions which would stir up any debris from the bottom of the tank.
This article from the Boat Galley explains in detail how you can polish your fuel. They list the tools needed and offer in step-by-step detail how to do it yourself. Read More
