Mercury - Fuel Line Hose 3/8 Inch Marine Fuel Line Gray Polymer Construction 8M0038563. Overview. There's a certain comfort that comes from knowing your fuel system is dialed in and ready for whatever the day brings. When you're pushing away from the dock before sunrise or easing back toward shore after a long afternoon, you want every part of your setup to feel dependable. A good fuel line might not be the flashiest piece of gear on your boat, but when it's right, everything else feels right to