Ignition Coil for Mercury 30HP 40HP EFI 3cyl | JLM Marine
This high-quality aftermarket ignition coil is engineered to fit Mercury 30HP and 40HP EFI 3-cylinder outboard engines. Designed to deliver reliable spark and consistent performance, this coil ensures your engine runs smoothly in all conditions.
This ignition coil directly replaces OEM part numbers 8M0045124 and 8M0034012, providing a cost-effective solution without compromising on quality or durability.
- Direct replacement for Mercury Marine Mercruiser ignition coils
- Compatible with EFI 3-cylinder outboard models
- Includes complete ignition coil assembly as shown
Part Number Cross-Reference
Use this table to confirm equivalent part numbers across OEM and aftermarket brands.
| Brand |
Part Number |
| Mercury Marine |
8M0045124 |
| Mercury Marine |
8M0034012 |
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 |
Notes |
| Mercury Marine Mercruiser |
30 EFI |
30 HP |
3-cylinder |
| Mercury Marine Mercruiser |
40 EFI |
40 HP |
3-cylinder |
Technical Specifications
| Specification |
Value |
| Part Type |
Ignition Coil |
| OEM Part Number |
8M0045124, 8M0034012 |
| Compatible Brand |
Mercury Marine Mercruiser |
| Engine Configuration |
3-Cylinder EFI |
| Horsepower Range |
30–40 HP |
Package Contents
This package includes:
Note: The package contains all the parts shown in the product images.
Installation Guide
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Disconnect the battery to ensure safety before starting any electrical work on your outboard engine.
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Locate the ignition coil on your Mercury 30HP or 40HP EFI 3-cylinder engine (refer to your engine's service manual or parts diagram).
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Disconnect the spark plug wire from the old ignition coil by pulling gently on the boot, not the wire.
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Unplug the electrical connector from the ignition coil by pressing the release tab and pulling the connector free.
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Remove the mounting bolts securing the old coil to the engine block using the appropriate wrench or socket.
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Lift out the old ignition coil carefully and set it aside.
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Position the new ignition coil in the same location, aligning the mounting holes with the engine block.
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Install and tighten the mounting bolts to secure the new coil, following manufacturer torque specifications if available.
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Reconnect the electrical connector to the new ignition coil, ensuring it clicks into place securely.
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Attach the spark plug wire to the new coil by pressing the boot firmly onto the terminal.
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Reconnect the battery and test the engine to verify proper ignition and smooth operation.
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Inspect all connections after the initial test run to ensure everything is secure and functioning correctly.
Troubleshooting & FAQ
Q: How do I know if my ignition coil needs replacing?
A: Common signs include difficulty starting the engine, rough idling, misfiring, loss of power, or complete failure to start. If your spark plugs are in good condition but you still experience these symptoms, the ignition coil may be faulty.
Q: How do I confirm this ignition coil fits my Mercury engine?
A: Verify that your engine is a Mercury 30HP or 40HP EFI 3-cylinder model. Cross-reference your current part number (8M0045124 or 8M0034012) with the specifications listed. You can also consult the Mercury parts diagrams linked above.
Q: Can I install this ignition coil myself?
A: Yes, if you have basic mechanical skills and tools. However, working with ignition systems requires caution. Always disconnect the battery first and follow proper safety procedures. Professional installation is recommended if you're unsure.
Q: How often should I replace the ignition coil?
A: Ignition coils typically last many years under normal use. Replace them only when symptoms of failure appear or during major engine overhauls. Regular maintenance and inspection can help identify issues early.
Q: Is this an OEM part or 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?
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Quality Assured: As a trusted manufacturer for over 20 years, we supply top marine brands globally.
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Fast Global Shipping: Free delivery worldwide in 5–15 days.
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Direct from Manufacturer: Competitive pricing without compromising quality.