Mercury - Quicksilver 816856T3 Quick-Disconnect Fuel Line Connector Kit Vintage Mercury & Mariner Outboards 5/16-Inch Line 816856T3. Overview. If you run an older Mercury or Mariner outboard, this part is one of those simple upgrades that just makes life easier. The Mercury 816856T3 Quick-Disconnect Fuel Line Connector Kit gives vintage engines a solid, no-leak connection where the fuel line meets the motor.. It's made from cast aluminum, not plastic, so it's tough enough to handle years of heat