Mercury - Fuel Tank Threaded Hose Barb Fitting Fuel System Hardware Stainless Steel 8M0058419. Overview. Every boater knows the feeling of settling into a smooth run, your engine responding cleanly with each push of the throttle. That kind of confidence comes from a fuel system built on solid, dependable parts - even the small ones. The Mercury Stainless Steel Fuel Tank Threaded Hose Barb Fitting (8M0058419) is one of those quiet heroes. It's the simple, sturdy connection that keeps fuel flowing