Mercury - Fuel Filter Cap Removal/Installation Tool Fuel System Service Precision Fit Part Number 896661. Overview. Anyone who's ever tried to remove a stubborn fuel filter cap knows that some jobs on an outboard are easier said than done. The Quicksilver 896661 Fuel Filter Cap Tool takes the fight out of that chore. It's one of those practical, well-made tools that makes routine maintenance feel smoother and far less frustrating. Whether you're doing a quick service before an early morning run