Mercury - Fuel Level Gauge Black Face 2-1/8" (52 mm) 79-8M0052844. Overview. The Mercury Fuel Level Gauge (79-8M0052844) gives you a clear, accurate view of your remaining fuel supply right from the dash. Designed with a black face, crisp white markings, and a glass lens, it's easy to read in bright sunlight or low light. It fits a standard 2-1/8" (52 mm) gauge hole and works with SmartCraft-equipped systems when compatible fuel level sensors are installed. It's durable, dependable, and matches