Check Valve Kit – Fits Mercury/Mariner 75 HP 4-Cylinder Outboards (Replaces 21-30430A13, 30430A5)
Check Valve Kit – Fits Mercury/Mariner 75 HP 4-Cylinder Outboards (Replaces 21-30430A13, 30430A5) 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 aftermarket Check Valve Kit is designed for Mercury and Mariner 75 HP 4-cylinder outboard engines with serial numbers 6432901 and up, 7208573 and up, or 9393856 and up. It is a crucial component used on the triangle fuel pump configuration to ensure proper fuel flow and prevent backflow.
It serves as a direct replacement for Mercury OEM part numbers 21-30430A13, 8M0084276, and 30430A5, ensuring a precise fit and function.
- Engineered for direct-fit installation.
- Compatible with standard marine gasoline.
- Specifically used on the triangle fuel pump assembly.
Part Number Matrix
Use this matrix to confirm equivalent references across OEM and aftermarket.
| Brand | Part Number | Superseded By |
|---|---|---|
| Mercury | 21-30430A13 | 8M0084276 |
| Mercury | 30430A5 |
Engine & Model Compatibility
Confirm your engine model/year in the table below.
Fitment for Mercury and Mariner models is determined by the engine serial number. Please verify your serial number falls within the specified ranges.
| Brand | Model | Rated HP | OEM Part No. | Notes |
|---|---|---|---|---|
| Mercury | 75 (4 CYL) | 75 | 21-30430A13 | Superseded by 8M0084276; For serial numbers 6432901 and up |
| Mercury | 75 (4 CYL) | 75 | 21-30430A13 | Superseded by 8M0084276; For serial numbers 7208573 and up |
| Mercury | 75 (4 CYL) | 75 | 21-30430A13 | Superseded by 8M0084276; For serial numbers 9393856 and up |
| Mariner | 75 (4 CYL) | 75 | 21-30430A13 | Superseded by 8M0084276; For serial numbers 6432901 and up |
| Mariner | 75 (4 CYL) | 75 | 21-30430A13 | Superseded by 8M0084276; For serial numbers 7208573 and up |
| Mariner | 75 (4 CYL) | 75 | 21-30430A13 | Superseded by 8M0084276; For serial numbers 9393856 and up |
Technical Specs
- Product Type
- Fuel Check Valve Kit
- Installation
- Direct replacement
- Fuel Type
- Marine gasoline
- Dimensions
- 12.0" L x 10.5" W x 1.5" H
- Other Technical Attributes
- Used on triangle fuel pump configuration
What’s in the Box
- 1 x Check Valve Kit (Replaces 21-30430A13/8M0084276)
Installation Notes
- Ensure the engine is off and cool, and disconnect the battery as a safety precaution.
- Relieve fuel system pressure according to your engine's service manual to prevent spills.
- Locate the existing check valve on the fuel pump assembly.
- Carefully place a rag below the connections to catch any residual fuel and disconnect the fuel lines.
- Remove the old check valve assembly.
- Install the new check valve kit, making sure any gaskets or seals are correctly seated.
- Securely reconnect the fuel lines to the new valve.
- Once installed, prime the fuel system as per your manufacturer’s guidelines.
- Reconnect the battery, start the engine, and carefully inspect for any leaks around the new valve.
Troubleshooting & FAQ
How do I confirm this kit fits my outboard?
This kit is specifically for Mercury/Mariner 75 HP 4-cylinder outboards. The most important step is to check your engine's serial number. It must match one of the following series: 6432901 and up, 7208573 and up, or 9393856 and up. Always cross-reference with your original part number if possible.
What are the symptoms of a failing fuel check valve?
A faulty check valve can cause several issues, including hard starting, long cranking times, poor idling, engine stalling, and reduced overall performance. This is because it fails to maintain fuel pressure in the line, allowing fuel to drain back towards the tank.
Where is this part located on the engine?
This check valve is a component of the triangle-shaped fuel pump assembly found on the specified Mercury and Mariner engines.
Can I install this part myself?
While installation is straightforward for those with mechanical experience, working with fuel systems carries inherent risks. We recommend professional installation to ensure safety and proper function. If doing it yourself, always follow the engine manufacturer's service manual.
What is the purpose of this valve?
The fuel check valve is a one-way valve that allows fuel to travel from the pump to the engine but prevents it from flowing backward. This maintains pressure in the fuel line, which is essential for quick starts and stable engine operation.
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.
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