Mercury - Fuel Line (100 ft.) Fuel System Hose Gray Polymer 8M0038500. Overview. If you've spent enough time on the water, you know that a dependable fuel line isn't just another piece of rigging - it's the quiet lifeline that keeps every trip running smooth. A good line doesn't kink when the sun is beating down, it doesn't stiffen when the temperatures drop, and it certainly doesn't surprise you with vapor lock halfway across the channel. That's why boaters stick with Mercury's fuel system part