300-8M0044991 Ignition Coil for Mercury Mariner Mercruiser | JLM Marine

300-8M0044991 Ignition Coil for Mercury Mariner Mercruiser

This ignition coil is engineered to fit a wide range of Mercury, Mariner, and Mercruiser engines, including 4-stroke 4-cylinder outboards from 35HP to 450HP and select sterndrive/inboard gas engines. Designed for reliable spark delivery across multiple horsepower platforms, it ensures consistent ignition performance in demanding marine environments.

This part directly replaces OEM numbers 8M0044991, 8M0029482, and 300-8M0044991, providing a cost-effective solution for routine maintenance or emergency repairs without compromising on quality.

• Compatible with Mercury, Mariner, and Mercruiser 4-stroke engines
• Fits outboards ranging from 35HP to 450HP and select V6/V8 sterndrive/inboard models
• Includes one complete ignition coil assembly

Part Number Cross-Reference

Use this table to confirm equivalent part numbers across OEM and aftermarket brands.

Compatible Engine Models

Confirm your engine model/year in the table below. For Mercury owners, here's a guide to help you identify your engine's serial/model: Mercury Serial Number Guide. You can also review exploded diagrams to verify part numbers: Mercury Parts Diagrams & Catalog.

Technical Specifications

Package Contents

This package includes:

• 1 × Ignition Coil

Installation Guide

1. Disconnect the battery: Always disconnect the negative battery terminal before beginning work on the ignition system to prevent electrical shock or short circuits.
2. Locate the faulty coil: Identify the ignition coil that needs replacement on your engine—refer to your service manual or parts diagram if necessary.
3. Disconnect electrical connectors: Carefully unplug the wiring harness connector from the old ignition coil.
4. Remove mounting hardware: Unscrew or unclip the coil from its mounting bracket or cylinder head using the appropriate tools.
5. Install the new coil: Position the replacement coil in the mounting location and secure it with the original hardware, tightening to the manufacturer's recommended torque specification.
6. Reconnect electrical connectors: Plug the wiring harness firmly back into the new ignition coil, ensuring a solid connection.
7. Reconnect the battery: Reattach the negative battery terminal.
8. Test the engine: Start the engine and verify smooth operation, listening for misfires or rough idling.

Troubleshooting & FAQ

Q: How do I confirm this ignition coil fits my engine?
A: Check the Compatible Engine Models table above for your brand, horsepower, and stroke type. You can also verify your engine's serial number using the guides linked in that section, or compare the OEM part numbers on your current coil with those listed in the Part Number Cross-Reference table.

Q: What are the common signs that an ignition coil needs replacement?
A: Typical symptoms include engine misfires, rough idling, hard starting, reduced power, poor fuel economy, and the engine not firing on one or more cylinders. If you experience any of these issues, testing or replacing the ignition coil is a good troubleshooting step.

Q: How often should I replace the ignition coil?
A: Ignition coils do not have a fixed replacement interval and are typically replaced only when they fail or show signs of malfunction. Regular engine inspections and addressing misfires promptly can help extend the life of ignition components.

Q: Will this work on both outboard and sterndrive/inboard engines?
A: Yes, this coil is compatible with select Mercury outboards (35HP–450HP), Mariner outboards (50HP–150HP), and Mercruiser sterndrive and inboard gas engines with 4-stroke 4-cylinder configurations as listed in the compatibility table.

Q: OEM vs. Aftermarket?
A: This listing is an aftermarket replacement part (not an OEM component). We build to OEM specifications using comparable-grade materials. Production is done in an ISO9002-certified facility, and each batch is inspected for consistent performance.

Q: How fast do you ship and how much does it cost?
A: We offer fast global shipping—typically 5–15 days worldwide—and standard shipping is free. Expedited options are available at checkout depending on your location.

Q: What is your warranty and return policy?
A: This product includes a 1-year warranty against manufacturing defects under normal use. If something goes wrong, contact our support team with your order details. Returns are accepted within our standard return window (unused & in original condition); please see our policy page or reach out for instructions.

Important Notes

• Verify that the product images and specifications match your original part. If discrepancies exist—even if your model is listed—do not proceed with the purchase.
• This product is an aftermarket replacement part and is not an OEM component.
• Professional installation is recommended to ensure safety and optimal performance.

Why Choose JLM MARINE?

• Quality Assured: As a trusted manufacturer for over 20 years, we supply top marine brands globally.
• Fast Global Shipping: Free delivery worldwide in 5–15 days.
• Direct from Manufacturer: Competitive pricing without compromising quality.