Mercury - Quicksilver 8288181 Drain Plug Portable Fuel Tanks Mercury 13.5-90HP 4-Stroke Outboards 8288181. Overview. A small but essential part, the Quicksilver 8288181 Drain Plug keeps your portable fuel tank sealed tight and ready for action. Made from stainless steel and plated black to match Mercury gearcases, it's designed to handle the demands of daily marine use without corrosion or leaks.. This plug fits most portable fuel tanks used on Mercury carbureted 13.5-90HP 4-stroke and 30-90HP 4