Water in the fuel is a big problem with boats...The tanks sweat and create a lot of moisture that gets thru regular fuel filters...A water seperater filter system works best....IF.!!....the element is changed regularly....Water just won't pass thru the passageways of a carb ver well....Keeps the fuel tank (s) full as possible and use a gas dryer of some sort...And of course water/gas mixture doesn't burn so well causing a lean condition and back fire...Just one of the many problems with boats....Damn things..