Diaphragm – Fits Mercury 2.5L V6 Outboards (Replaces 14479-1)
Diaphragm – Fits Mercury 2.5L V6 Outboards (Replaces 14479-1) is backordered and will ship as soon as it is back in stock.
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Worry-free returns
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.).
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Delivery and Shipping
Delivery and Shipping
Free standard shipping on all orders under 1 KG
Product Details
This fuel pump Diaphragm – Fits Mercury 2.5L V6 Outboards and is engineered for a wide range of V6 engines from 150 to 225 HP, covering models from the late 1990s through 2018. It provides a reliable seal and durable performance for essential fuel system repairs.
It serves as a direct interchange for several common part numbers, including GLM 13812, Mercury 14479-1, and Sierra 18-3701.
- Engineered for a direct, hassle-free installation.
- Essential component for fuel pump repairs and maintenance.
- Designed for gasoline-fueled marine environments.
Part Number Matrix
Use this matrix to confirm equivalent references across OEM and aftermarket.
| Brand | Part Number |
|---|---|
| GLM | 13812 |
| Mercury | 14479-1 |
| Sierra | 18-3701 |
Engine & Model Compatibility
Confirm your engine model/year in the table below.
This diaphragm is compatible with a range of Mercury V6 outboard engines. Please verify your specific model and horsepower rating below.
| Brand | Model | Rated HP | Years | OEM Part No. | Notes |
|---|---|---|---|---|---|
| Mercury | V6 2.5L Outboard | 150 | 14479-1 | Fuel pump diaphragm | |
| Mercury | V6 2.5L Outboard | 175 | 14479-1 | Including OptiMax models | |
| Mercury | V6 2.5L Outboard | 200 | 14479-1 | Including OptiMax models | |
| Mercury | V6 2.5L Outboard | 225 | 14479-1 | Including OptiMax models | |
| Mercury | 3L Pro XS | 150 | Up to 2018 | 14479-1 | For 6 Cyl 3.6265 Bore |
| Mercury | 3L EFI | 225 | Up to 2018 | 14479-1 | For 6 Cyl 3.625 Bore |
Technical Specs
- Product Type
- Fuel Pump Diaphragm
- Installation
- Direct replacement
- Fuel Type
- Gasoline
- Application
- For fuel pump repairs in Mercury outboard engines
- Dimensions
- 13.0" L x 11.0" W x 1.0" H
What’s in the Box
- 1 x Diaphragm (Replaces 14479-1)
Installation Notes
- Disconnect the negative battery terminal to ensure electrical safety.
- Carefully relieve any pressure in the fuel system according to your service manual.
- Note the orientation of and disconnect the fuel lines from the pump.
- Remove the fuel pump assembly from the engine block.
- Disassemble the pump housing to expose the old diaphragm.
- Thoroughly clean the mating surfaces of the pump housing, removing any old gasket material.
- Install the new diaphragm, making sure it is correctly aligned.
- Reassemble the fuel pump and torque fasteners to manufacturer specifications.
- Reinstall the pump assembly onto the engine.
- Reconnect the fuel lines and battery terminal.
- Prime the fuel system and carefully inspect for any leaks before starting the engine.
Troubleshooting & FAQ
What engines does this diaphragm fit?
It is designed for Mercury 2.5L V6 engines (150–225 HP) from the late 1990s to 2018, along with certain 3L Pro XS and EFI models. Always consult the detailed compatibility table to confirm fitment for your specific engine.
Is this diaphragm compatible with Mercury OptiMax models?
Yes, our data confirms it is compatible with OptiMax versions of the 175, 200, and 225 HP 2.5L V6 outboards.
What are the signs of a failed fuel pump diaphragm?
Common symptoms include poor engine performance, stalling at idle, difficulty starting, rough running, or visible fuel leaks from the fuel pump weep hole or housing seams.
How often should a fuel pump diaphragm be replaced?
There is no universal replacement interval. It should be inspected during routine fuel system service and replaced immediately if you notice signs of wear, hardening, cracking, or fuel saturation.
What's the difference between this part and the OEM Mercury 14479-1?
This is an aftermarket component built to meet or exceed original equipment manufacturer (OEM) specifications for fit, material durability, and performance. It provides a reliable, cost-effective alternative to the original part.
Does this item include gaskets or other hardware?
No, this package contains one fuel pump diaphragm only, as shown in the product images and listed under "What’s in the Box." Additional gaskets or hardware are not included.
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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