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300-8M0044991 Ignition Coil for Mercury Mariner Mercruiser | JLM Marine
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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.
| Brand | Part Number |
|---|---|
| Mercury | 8M0044991 |
| Mercury | 8M0029482 |
| Mercury | 300-8M0044991 |
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.
| Brand | Model | Rated HP | Stroke | Notes |
|---|---|---|---|---|
| Mercury | Outboard | 35HP | 4-Stroke | 4-Cylinder Engine |
| Mercury | Outboard | 40HP | 4-Stroke | 4-Cylinder Engine |
| Mercury | Outboard | 50HP | 4-Stroke | 4-Cylinder Engine |
| Mercury | Outboard | 60HP | 4-Stroke | 4-Cylinder Engine |
| Mercury | Outboard | 75HP | 4-Stroke | 4-Cylinder Engine |
| Mercury | Outboard | 80HP | 4-Stroke | 4-Cylinder Engine |
| Mercury | Outboard | 90HP | 4-Stroke | 4-Cylinder Engine |
| Mercury | Outboard | 100HP | 4-Stroke | 4-Cylinder Engine |
| Mercury | Outboard | 115HP | 4-Stroke | 4-Cylinder Engine |
| Mercury | Outboard | 135HP | 4-Stroke | 4-Cylinder Engine |
| Mercury | Outboard | 150HP | 4-Stroke | 4-Cylinder Engine |
| Mercury | Outboard | 175HP | 4-Stroke | 4-Cylinder Engine |
| Mercury | Outboard | 200HP | 4-Stroke | 4-Cylinder Engine |
| Mercury | Outboard | 225HP | 4-Stroke | 4-Cylinder Engine |
| Mercury | Outboard | 250HP | 4-Stroke | 4-Cylinder Engine |
| Mercury | Outboard | 300HP | 4-Stroke | 4-Cylinder Engine |
| Mercury | Outboard | 450HP | 4-Stroke | 4-Cylinder Engine |
| Mariner | Outboard | 50HP | 4-Stroke | 4-Cylinder Engine |
| Mariner | Outboard | 60HP | 4-Stroke | 4-Cylinder Engine |
| Mariner | Outboard | 75HP | 4-Stroke | 4-Cylinder Engine |
| Mariner | Outboard | 80HP | 4-Stroke | 4-Cylinder Engine |
| Mariner | Outboard | 90HP | 4-Stroke | 4-Cylinder Engine |
| Mariner | Outboard | 100HP | 4-Stroke | 4-Cylinder Engine |
| Mariner | Outboard | 115HP | 4-Stroke | 4-Cylinder Engine |
| Mariner | Outboard | 150HP | 4-Stroke | 4-Cylinder Engine |
| Mercruiser | Sterndrive Gas Engine | 200HP | 4-Stroke | 4.5L 274 CID V6 |
| Mercruiser | Sterndrive Gas Engine | 250HP | 4-Stroke | 4.5L 274 CID V6 |
| Mercruiser | Sterndrive Gas Engine | 300HP | 4-Stroke | 6.2L 377 CID V8 |
| Mercruiser | Sterndrive Gas Engine | 350HP | 4-Stroke | 6.2L 377 CID V8 |
| Mercruiser | Inboard Gas Engine | — | 4-Stroke | 6.2L 377 CID V8 |
Technical Specifications
| Specification | Value |
|---|---|
| OEM Part Number | 300-8M0044991 |
| Replaces Part Numbers | 8M0044991, 8M0029482, 300-8M0044991 |
| Application | 4-Stroke 4-Cylinder Engine |
| Type | Ignition Coil |
Package Contents
This package includes:
- 1 × Ignition Coil
Installation Guide
- Disconnect the battery: Always disconnect the negative battery terminal before beginning work on the ignition system to prevent electrical shock or short circuits.
- Locate the faulty coil: Identify the ignition coil that needs replacement on your engine—refer to your service manual or parts diagram if necessary.
- Disconnect electrical connectors: Carefully unplug the wiring harness connector from the old ignition coil.
- Remove mounting hardware: Unscrew or unclip the coil from its mounting bracket or cylinder head using the appropriate tools.
- 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.
- Reconnect electrical connectors: Plug the wiring harness firmly back into the new ignition coil, ensuring a solid connection.
- Reconnect the battery: Reattach the negative battery terminal.
- 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.
We can ship to virtually any address in the world with free shipping available for most regions.
For our typical US and Canadian customers , our shipping timeframes are as follows:
- Amazon FBA: orders will be delivered within 1-5 business days after placing the order (during certain special periods such as major promotions, Christmas, etc., the delivery time of Amazon FBA may be affected).
- US warehouse shipment: orders will be delivered within 5 days after placing the order.
- China warehouse shipment: orders will be delivered about 12 days after placing the order.
When you place an order, we will estimate shipping and delivery dates for you based on the availability of your items and the shipping options you choose. Depending on the shipping provider you choose, shipping date estimates may appear on the shipping quotes page.
Please also note that the shipping rates for many items we sell are weight-based. The weight of any such item can be found on its detail page. To reflect the policies of the shipping companies we use, all weights will be rounded up to the next full pound.
Founded in 2002, JLM Marine has established itself as a dedicated manufacturer of high-quality marine parts, based in China. Our commitment to excellence in manufacturing has earned us the trust of top marine brands globally.
As a direct supplier, we bypass intermediaries, which allows us to offer competitive prices without compromising on quality. This approach not only supports cost-efficiency but also ensures that our customers receive the best value directly from the source.
We are excited to expand our reach through retail channels, bringing our expertise and commitment to quality directly to boat owners and enthusiasts worldwide.
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