Water and fuel don't mix - at least, not if you want your outboard running the way it should. That's where the Mercury Marine Water in Fuel Sensor - 8M0157779 comes into play. Mounted directly in your fuel system, this sensor constantly monitors for water contamination, giving you an early heads-up before moisture works its way into injectors, pumps, or other critical components.. Engineered specifically for select Mercury outboards, this OEM sensor integrates seamlessly with the fuel filter assembly, ensuring accurate readings without false alarms. Its durable housing and corrosion-resistant contacts are built to hold up under harsh marine conditions, whether your boat's working in saltwater, freshwater, or bouncing between the two. Spotting trouble early gives you time to take action - protecting your engine from the kinds of damage that start small but can cut a trip short fast.. Key Features & Benefits:. Genuine Mercury part for accurate water detection and early warnings. Corrosio