Mercury - 6-Pin to 2-Pin WIF Sensor Harness Fuel/Water Interface Lead 84-8M0060420. Overview. When a boat's tank-level reading doesn't show up on the display, it often comes down to the engine not receiving a clean signal from the Water-In-Fuel (WIF) sensor. The Mercury 84-8M0060420 Harness fixes that gap. It connects a 6-pin engine lead to a 2-pin WIF sensor so the engine can properly detect, report, and alert for water contamination in the fuel system. It's a simple, targeted solution meant fo