Mercury - Carburetor Diaphragm Kit for 30-65hp 2-Stroke Outboards Fuel System Rebuild Kit Precision Marine Components 857005A1. Overview. There's something deeply reassuring about knowing your outboard will respond the moment you nudge the throttle. No hesitation, no stumbling-just that smooth surge you feel in your hands and hear in the engine's tone. When a carburetor starts to wear, you can sense the difference long before you see it. That's why the Mercury Marine part number 857005A1 Carbure