Mercury - Inline Fuel Filter Fuel System Protection Marine-Grade Construction 864572. Overview. Ask anyone who spends their weekends on the water and they'll tell you-clean fuel is everything. A boat can look great, sound great, and even run great… right up until a little debris sneaks its way into the fuel system. That's when the day takes a turn. With the Mercury Marine 864572 Inline Fuel Filter, you get the kind of quiet reassurance every boater appreciates. It sits tucked between your fuel t