Mercury - Carburetor Float Precision Fuel System Component Marine Composite 91691. Overview. Every boater knows that smooth running starts with clean, steady fuel delivery. When you're working with a smaller 2-stroke outboard-something in that 10 to 20 horsepower range-you rely on it for everything from pushing you out to the morning fishing grounds to easing you back through a no-wake zone at sunset. The Quicksilver 91691 Carburetor Float might not look like much at first glance, but its job is