Mercury - Quicksilver 819503A5 Solenoid Kit Mercury TwoStroke & Jet Outboards 819503A5. Overview. When your outboard hesitates to turn over, the solenoid is often the culprit. The Mercury 819503A5 Solenoid Kit is a genuine replacement for select Mercury TwoStroke and Jet outboards, restoring strong, reliable starts with every turn of the key.. This OEM solenoid is built for harsh marine conditions - sealed to resist moisture and corrosion, and tested to Mercury's own standards for durability and