Fuel Pump Diaphragm Kit – Fits Mercury/Mariner 90/115/140 HP Inline 6-Cylinder
Fuel Pump Diaphragm Kit – Fits Mercury/Mariner 90/115/140 HP Inline 6-Cylinder 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.).
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
Product Details
This Fuel Pump Diaphragm Kit is designed to restore fuel system performance in Mercury and Mariner 90-140 HP, 6-cylinder inline outboard engines manufactured between 1979 and 1988. It serves as a direct-fit repair solution for aging or damaged fuel pump components.
This kit provides a direct interchange for Mercury OEM part 89031A3 (which supersedes 66599A3), GLM 40370, and EMP 1399-00115.
- Installs directly into the original equipment fuel pump housing.
- Engineered as a complete repair kit for carbureted outboard engines.
- Includes the necessary diaphragm, seals, and screen for a comprehensive service.
Part Number Matrix
Use this matrix to confirm equivalent references across OEM and aftermarket.
| Brand | Part Number | Superseded By |
|---|---|---|
| Mercury | 66599A3 | 89031A3 |
| Mercury | 89031A3 | |
| GLM | 40370 | |
| EMP | 1399-00115 |
Engine & Model Compatibility
Confirm your engine model/year in the table below.
Mercury/Mariner Outboards: This kit fits select inline 6-cylinder models from 90 to 140 HP produced from 1979 to 1988. Check your serial number or original part number to verify fitment.
| Brand | Model | Rated HP | Stroke | Years | OEM Part No. | Notes |
|---|---|---|---|---|---|---|
| Mariner | 90 [EL] | 90 | 2-Stroke | 1979 | 89031A3 | Serial: 7090529 |
| Mariner | 90 [ELPT] | 90 | 2-Stroke | 1979 | 89031A3 | Serial: 7090629 |
| Mariner | 115 [EL] | 115 | 2-Stroke | 1979 | 89031A3 | Serial: 7115529 |
| Mariner | 115 [ELPT] | 115 | 2-Stroke | 1979 | 89031A3 | Serial: 7115629 |
| Mariner | 140 [ELPT] | 140 | 2-Stroke | 1979 | 89031A3 | Serial: 7140629 |
| Mercury | 140 [ELPT] | 140 | 2-Stroke | 1979 | 89031A3 | Serial: 1140629 |
| Mercury | 90 [6 Cyl] | 90 | 2-Stroke | 1980–1982 | 89031A3 | Inline 6-cylinder |
| Mercury | 115 [6 Cyl] | 115 | 2-Stroke | 1980–1983 | 89031A3 | Inline 6-cylinder |
| Mercury | 90 INLINE | 90 | 2-Stroke | 1984–1988 | 89031A3 | 6-cylinder |
| Mercury | 115 INLINE | 115 | 2-Stroke | 1984–1988 | 89031A3 | 6-cylinder |
Technical Specs
- Product Type
- Fuel Pump Diaphragm Kit
- Installation
- Direct replacement for original equipment
- Fuel Type
- Gasoline
- Connection
- Integrated in fuel pump assembly
- Dimensions
- 6.0" L x 7.5" W x 1.5" H
- Warranty
- Varies by manufacturer
- Other Technical Attributes
- Fuel pump repair component for carbureted outboard engines
What’s in the Box
- 3 x Cover To Fuel Pump O-Ring (35480)
- 1 x Inlet Screen (59072)
- 1 x O-Ring (38933)
- 1 x Diaphragm Assembly (89031A3)
Installation Notes
- Disconnect the boat's battery and relieve pressure from the fuel system.
- Carefully disconnect the fuel inlet and outlet lines from the fuel pump.
- Remove the mounting bolts securing the fuel pump to the engine block and detach the pump.
- Disassemble the pump housing, taking care to note the orientation of all screws, gaskets, and internal parts.
- Remove the old diaphragm, o-rings, and inlet screen.
- Thoroughly clean the housing surfaces, removing any old gasket material or debris.
- Install the new diaphragm, screen, and O-rings provided in the kit.
- Reassemble the pump housing, ensuring the diaphragm is properly seated and screws are tightened evenly in a star pattern.
- Mount the reassembled pump back onto the engine block.
- Reconnect the fuel lines securely.
- Reconnect the battery, prime the fuel system, and carefully check for any leaks before starting the engine.
Troubleshooting & FAQ
How do I confirm this diaphragm kit fits my specific engine?
First, check your engine model, horsepower, and year against our compatibility table. Second, verify that your existing fuel pump uses OEM part number 89031A3 or a superseded/aftermarket equivalent listed in our Part Number Matrix. If you are unsure, visually compare your old diaphragm to the product photos.
What are the signs of a failing fuel pump diaphragm?
Common symptoms include the engine hesitating, sputtering at high speeds, bogging down under acceleration, or difficulty starting. You may also notice fuel leaking externally from the fuel pump's weep hole, which is a definitive sign of a ruptured diaphragm.
Is this a complete fuel pump assembly?
No, this is a repair kit for the OEM fuel pump. It contains the essential wear items—the diaphragm, screen, and seals—needed to rebuild and restore the function of your existing pump assembly. It does not include the metal pump housing.
How often should a fuel pump diaphragm be replaced?
There is no fixed replacement interval. Diaphragms wear out over time due to fuel exposure and constant flexing. It is good practice to inspect the diaphragm during annual service and replace it if it appears stiff, cracked, or shows any signs of deterioration.
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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