Sierra 18-99428 Trigger Assembly for Mercury Mariner 4-Cylinder Outboard

The Sierra 18-99428 is a premium aftermarket trigger assembly designed specifically for 4-cylinder Mercury and Mariner outboard engines. This critical ignition component mounts beneath the flywheel and works in conjunction with the ignition system to provide precise timing signals that control spark delivery to the engine.

Key Features:

• Precision-engineered replacement trigger assembly for 4-cylinder applications
• Designed to meet or exceed OEM specifications for reliable performance
• Manufactured with quality materials to withstand harsh marine environments
• Direct replacement for Mercury/Mariner trigger assemblies
• Essential component for maintaining proper ignition timing and engine performance

Sierra is a trusted name in marine aftermarket parts, offering professional-grade components engineered for durability and dependability. The trigger assembly is a wear item that should be inspected during routine maintenance and replaced if showing signs of corrosion, damage, or when experiencing ignition-related issues. Proper trigger function is essential for smooth engine operation, reliable starting, and optimal fuel efficiency.