CDI Unit Assembly – Fits Yamaha 40HP E40 Series Outboard Motors (Replaces 6F6-85540-00, 6F6-85540-01)
CDI Unit Assembly – Fits Yamaha 40HP E40 Series Outboard Motors (Replaces 6F6-85540-00, 6F6-85540-01) is backordered and will ship as soon as it is back in stock.
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Worry-free returns
You may return most new, unopened items within 7 days of delivery for a full refund. We'll also pay the return shipping costs if the return is a result of our error (you received an incorrect or defective item, etc.).
You should expect to receive your refund within four weeks of giving your package to the return shipper, however, in many cases you will receive a refund more quickly. This time period includes the transit time for us to receive your return from the shipper (5 to 10 business days), the time it takes us to process your return once we receive it (3 to 5 business days), and the time it takes your bank to process our refund request (5 to 10 business days).
If you need to return an item, simply login to your account, view the order using the "Complete Orders" link under the My Account menu and click the Return Item(s) button. We'll notify you via e-mail of your refund once we've received and processed the returned item.
Delivery and Shipping
Delivery and Shipping
Free standard shipping on all orders under 1 KG
CDI Unit Assembly – Fits Yamaha 40HP E40 Series Outboard Motors (Re...
Product Details
This CDI Unit Assembly is a direct-fit replacement for Yamaha 40HP E40 series outboard motors, including E40G, E40J, and various other 2-stroke models. It is designed to restore ignition performance and ensure reliable engine operation, serving as a crucial component of your motor's electrical system.
The unit provides a direct interchange for Yamaha OEM part numbers 6F6-85540-00 and 6F6-85540-01.
- Installs on the outboard motor using the existing electrical wiring harness.
- Engineered for 2-cylinder, 40HP 2-stroke gasoline applications.
- Durable black plastic housing protects internal electronics from the marine environment.
Part Number Matrix
Use this matrix to confirm equivalent references across OEM and aftermarket.
| Brand | Part Number |
|---|---|
| Yamaha | 6F6-85540-00 |
| Yamaha | 6F6-85540-01 |
Engine & Model Compatibility
Confirm your engine model/year in the table below.
This part is designed for compatibility with specific Yamaha 2-stroke outboards.
| Brand | Model | Rated HP | Stroke | OEM Part No. |
|---|---|---|---|---|
| Yamaha | E40G | 40 | 2-Stroke | 6F6-85540-00/01 |
| Yamaha | E40J | 40 | 2-Stroke | 6F6-85540-00/01 |
| Yamaha | 40MH | 40 | 2-Stroke | 6F6-85540-00/01 |
| Yamaha | E40M | 40 | 2-Stroke | 6F6-85540-00/01 |
| Yamaha | E40W | 40 | 2-Stroke | 6F6-85540-00/01 |
| Yamaha | 40WH | 40 | 2-Stroke | 6F6-85540-00/01 |
| Yamaha | 40W | 40 | 2-Stroke | 6F6-85540-00/01 |
Technical Specs
- Product Type
- CDI Unit Assembly (Ignition Module)
- Installation
- Outboard Motor
- Fuel Type
- Gasoline
- Connection
- Electrical Wiring Harness
- Housing Material
- Plastic
- Housing Color
- Black
- Dimensions
- 10.0 x 0.08 x 0.03
- Weight
- 0.16 kg (0.35 lb)
- Other Technical Attributes
- For 2-cylinder engines, 40HP 2-stroke applications
What’s in the Box
- 1 x CDI Unit Assembly (6F6-85540-00/6F6-85540-01)
Installation Notes
- Disconnect the battery leads to prevent electrical shorts.
- Locate the existing CDI unit on the engine block. Note the wiring connections.
- Carefully disconnect the wiring harness from the old CDI module.
- Unbolt and remove the old unit from its mounting point.
- Mount the new CDI unit securely in the same location.
- Reconnect the wiring harness, ensuring a snug fit.
- Reconnect the battery and test engine operation to confirm proper function.
Troubleshooting & FAQ
How do I know if my CDI unit has failed?
Common signs of a failing CDI unit include no-start conditions, engine misfires (especially at high RPM), intermittent stalling, weak or no spark at the plugs, and backfiring. A definitive diagnosis can be made by testing the spark with an inline tester and checking the electrical output according to your service manual.
Is this part difficult to install?
Installation is straightforward for those with basic mechanical skills. It involves disconnecting the battery, unplugging the old unit's wiring harness, unbolting it, and reversing the process with the new part. However, if you are not comfortable working on your engine's electrical system, professional installation is recommended.
Will this fit Yamaha models not listed in the compatibility table?
It might, but we can only guarantee fitment for the models listed. Purchasing for an unlisted model is done at your own risk. Always compare the photos, specifications, and part numbers (6F6-85540-00, 6F6-85540-01) to your original part before ordering.
What is the main difference between this and the original Yamaha part?
This is an aftermarket part designed to function identically to the OEM version. While it may have slight cosmetic differences, it is built to match the original's performance specifications and connection type for a direct replacement.
Do I need to do anything after installing the new CDI?
No special tuning is required. After installation, it is good practice to test the engine at various RPMs to ensure it is running smoothly and that the previous ignition issues have been resolved. Check for any loose connections after the first run.
OEM vs. Aftermarket?
This listing is an aftermarket replacement (not OEM). Built to OEM-level specifications with comparable materials. Manufactured in an ISO 9002 facility, batch-inspected for consistency.
Shipping speed & cost
We ship worldwide quickly—typical transit 5–15 days. Standard shipping is free; expedited options appear at checkout where available.
Warranty & returns
Covered by a 1-year warranty against manufacturing defects under normal use. If issues arise, contact support with your order details. Returns are accepted within our standard window (unused & in original condition). See our policy page or reach out for instructions.
Safety & Important Info
- Verify images/specifications vs your original part. If anything differs—even if your model appears compatible—do not purchase.
- This is an aftermarket replacement, not an OEM component.
- Professional installation is recommended for safety and performance.
About Sea Sierra
- Pro-Grade Standards — We supply marine parts engineered to OEM-level tolerances and tested for real-world conditions.
- Fast Global Fulfillment — Free standard delivery to most regions in 5–15 days.
- Manufacturer-Direct Value — Fair pricing without compromising on materials or QC.
Payment & Security
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