Mercury - Bullet Connector Harness Adapter 2-Pin WIF Sensor Link 84-8M0060421. Overview. Smaller engines often use simple bullet-style connectors for their fuel and paddle harnesses, which can make it tricky to tie in a modern Water-In-Fuel (WIF) sensor. The Mercury 84-8M0060421 Bullet Connector Harness Adapter fixes that mismatch. It converts the engine's bullet connector lead into a clean 2-pin connection so the WIF sensor can report correctly. It's a small, practical adapter designed for 150