Check Valve Kit – Fits Mercury/Mariner 90-150 HP Outboards (Replaces 21-30430A7)
Check Valve Kit – Fits Mercury/Mariner 90-150 HP Outboards (Replaces 21-30430A7) 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 Check Valve Kit is designed for various Mercury and Mariner 6-cylinder outboard motors from 90 to 150 HP, generally produced between 1970 and 1984, including the 900, 1150, 1400, and 1500 series. It ensures proper fuel flow and prevents backflow within the fuel system.
This component serves as a direct replacement for Mercury/Mercruiser part number 21-30430A7 and Mercury/Mariner part number 30430A7.
- Installs as a critical component in the fuel system assembly.
- Designed for use with gasoline fuel systems.
- Connects the fuel pump and fuel line assembly.
Part Number Matrix
Use this matrix to confirm equivalent references across OEM and aftermarket.
| Brand | Part Number |
|---|---|
| Mercury/Mercruiser | 21-30430A7 |
| Mercury/Mariner | 30430A7 |
Engine & Model Compatibility
Confirm your engine model/year in the table below.
For Mercury and Mariner outboards, verify your model and serial number range to ensure a precise fit.
| Brand | Model | Rated HP | OEM Part No. | Notes |
|---|---|---|---|---|
| Mercury | 900, 90 | 90 | 21-30430A7 | Serial #4845301-5299505 |
| Mercury | 900, 90 | 90 | 21-30430A7 | Serial #7111698-7123762 |
| Mariner | 115 (6 CYL.) | 115 | 21-30430A7 | Serial #4865178-5430526 |
| Mariner | 115 (6 CYL.) | 115 | 21-30430A7 | Serial #8057045-8062459 |
| Mercury | 1150 | 115 | 21-30430A7 | Serial #3525441-4855152 |
| Mercury | 1150 | 115 | 21-30430A7 | Serial #7010763-7112248 |
| Mercury | 1150 | 115 | 21-30430A7 | Serial #8008665-8051949 |
| Mercury | 1150, 115 | 115 | 21-30430A7 | Serial #4855153-5314655 |
| Mercury | 1150, 115 | 115 | 21-30430A7 | Serial #7112248-7131212 |
| Mercury | 1150, 115 | 115 | 21-30430A7 | Serial #8051950-8061119 |
| Mariner | 140 | 140 | 21-30430A7 | Serial #5088444-5443029 |
| Mariner | 140 | 140 | 21-30430A7 | Serial #8055605-8062459 |
| Mercury | 1400, 140 | 140 | 21-30430A7 | Serial #4865678-5327662 |
| Mercury | 1400, 140 | 140 | 21-30430A7 | Serial #7112773-7132512 |
| Mercury | 1400, 140 | 140 | 21-30430A7 | Serial #8052650-8052879 |
| Mercury | 1500 | 150 | 21-30430A7 | Serial #3502806-4865677 |
| Mercury | 1500 | 150 | 21-30430A7 | Serial #7010533-7112772 |
| Mercury | 1500 | 150 | 21-30430A7 | Serial #8005615-8052649 |
| Mercury | 1500XS | 150 | 21-30430A7 | Serial #4868648-5327662 |
Technical Specs
- Product Type
- Check Valve Kit
- Installation
- Fuel System Component
- Fuel Type
- Gasoline
- Connection
- Fuel Pump & Fuel Line Assembly
- Dimensions
- 11.0" L x 10.0" W x 2.0" H
- Weight
- 0.045 kg (0.1 lb)
- Warranty
- 30 days (Green Bay Prop)
What’s in the Box
- 1 x Check Valve Kit (replaces 21-30430A7/30430A7)
Installation Notes
- Ensure the engine is off, cool, and disconnected from the battery.
- Safely relieve pressure from the fuel system by consulting your service manual.
- Place absorbent rags around the existing check valve to catch any fuel spillage.
- Carefully disconnect the fuel lines from the old valve.
- Remove the old check valve from its mounting.
- Install the new check valve, making sure it is oriented correctly for fuel flow.
- Securely reconnect the fuel lines to the new valve.
- Once installed, prime the fuel system and meticulously check all connections for leaks before starting the engine.
Troubleshooting & FAQ
How do I know if this check valve fits my engine?
This kit is designed for a specific range of Mercury and Mariner 6-cylinder outboards (90-150 HP). The most reliable way to confirm fitment is to match your engine's model and serial number against the compatibility table on this page. Also, verify that your original part number is listed as a direct replacement (21-30430A7 or 30430A7).
What are the signs of a failing fuel check valve?
Common symptoms include difficulty starting the engine, stalling, rough idling, or a loss of engine power. A failed check valve can allow fuel to drain back to the tank, causing the fuel pump to lose its prime.
Can I install this part myself?
Installation is straightforward for those with mechanical experience but involves working with the fuel system. It requires relieving fuel pressure and handling gasoline safely. If you are not comfortable with these procedures, professional installation is recommended.
What is the purpose of a fuel check valve?
A check valve is a one-way valve that allows fuel to flow from the fuel tank to the engine but prevents it from flowing backward. This maintains pressure in the fuel line, ensuring a steady supply of fuel for consistent engine performance.
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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