Mercury - Fuel Tank Connection with Fuel Demand Valve Portable Fuel System Marine-Grade Construction 8M0054714. Overview. There's a certain calm that settles in when your fuel system just works-no hiccups, no pressure burps, no surprises when you squeeze the primer bulb before heading out. That's the kind of trust the Quicksilver 8M0054714 Fuel Tank Connection with Fuel Demand Valve is built for. Whether you're running a small outboard on a quiet morning drift or keeping a portable tank onboard