Fuel Connector Cap – Fits Mercury 4–30 HP (Replaces Mercury 878311, Suzuki 65727-91JL0, Tohatsu 3H6-70262-0)
Fuel Connector Cap – Fits Mercury 4–30 HP (Replaces Mercury 878311, Suzuki 65727-91JL0, Tohatsu 3H6-70262-0) is backordered and will ship as soon as it is back in stock.
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Worry-free returns
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Delivery and Shipping
Delivery and Shipping
Free standard shipping on all orders under 1 KG
Fuel Connector Cap – Fits Mercury 4–30 HP (Replaces Mercury 878311,...
Product Details
This Fuel Connector Cap is designed to seal the fuel connection on integral fuel tanks for Mercury outboard engines. It is compatible with various Mercury models from 4 HP to 30 HP, primarily 4-stroke engines.
This part is a direct replacement for Mercury 878311, Suzuki 65727-91JL0, Tohatsu 3H6-70262-0, and QuickSilver 878311.
- Easy screw-on installation.
- Designed for gasoline-fueled integral (built-in) fuel tanks.
- Package includes one cap.
Part Number Matrix
Use this matrix to confirm equivalent references across OEM and aftermarket.
| Brand | Part Number | Notes |
|---|---|---|
| Mercury | 878311 | |
| QuickSilver | 878311 | |
| Suzuki | 65727-91JL0 | Cross reference to Mercury 878311 |
| Tohatsu | 3H6-70262-0 | Cross reference to Mercury 878311 |
Engine & Model Compatibility
Confirm your engine model/year in the table below.
This cap fits a wide range of Mercury 4-stroke outboards with integral fuel tanks. Please verify your HP rating against the compatible models listed.
| Brand | Model | Rated HP | Stroke | Years | OEM Part No. | Notes |
|---|---|---|---|---|---|---|
| Mercury | Multiple | 4 | 4-Stroke | 878311 | For integral fuel tanks | |
| Mercury | Multiple | 5 | 4-Stroke | 878311 | For integral fuel tanks | |
| Mercury | Multiple | 6 | 4-Stroke | 878311 | For integral fuel tanks | |
| Mercury | Multiple | 8 | 4-Stroke | 878311 | For integral fuel tanks | |
| Mercury | Multiple | 9.9 | 4-Stroke | 878311 | For integral fuel tanks | |
| Mercury | Multiple | 10 | 4-Stroke | 878311 | For integral fuel tanks | |
| Mercury | Multiple | 15 | 4-Stroke | 878311 | For integral fuel tanks | |
| Mercury | Multiple | 20 | 4-Stroke | 878311 | For integral fuel tanks | |
| Mercury | Multiple | 25 | 4-Stroke | 878311 | For integral fuel tanks | |
| Mercury | Multiple | 30 | 4-Stroke | 878311 | For integral fuel tanks |
Technical Specs
- Product Type
- Fuel Connector Cap
- Installation
- Screw-on
- Fuel Type
- Gasoline
- Connection
- Integral fuel tank inlet
- Housing Material
- Rubber
- Housing Color
- Black
- Other Attributes
- For use with integral (built-in) fuel tanks
What’s in the Box
- 1 x Cap (Replaces 878311)
Installation Notes
- Ensure the engine is off and in a well-ventilated area.
- Carefully unscrew the old fuel cap to release any built-up pressure.
- Remove the old cap and inspect the sealing surface on the tank for dirt or damage.
- Wipe the tank's inlet threads and sealing surface clean with a lint-free cloth.
- Position the new cap and screw it on by hand until it is snug. Do not overtighten.
- After installation, check for any signs of fuel leakage around the cap before operating the engine.
Troubleshooting & FAQ
Does this cap fit all Mercury 4–30 HP models?
This cap is designed for Mercury 4-stroke outboards from 4 HP to 30 HP that use an integral (built-in) fuel tank. It may not fit models with connections for external fuel tanks. Always verify your part number (878311) and check that your setup uses an integral tank.
What are the signs that my fuel connector cap needs to be replaced?
Common signs of a failing cap include visible cracks or brittleness in the rubber, a loose or improper fit, a persistent smell of fuel around the engine, or fuel leaking from the cap area. A worn-out seal can compromise safety and fuel efficiency.
Is this a genuine OEM part?
No, this is an aftermarket part designed to meet or exceed OEM specifications. It provides a reliable, cost-effective alternative to the original Mercury 878311, Suzuki 65727-91JL0, and Tohatsu 3H6-70262-0 parts.
Can I use this cap for a different fuel type, like diesel?
This cap is specifically designed for use with gasoline. Using it with other fuel types is not recommended, as the material may not be compatible and could degrade, leading to leaks or failure.
How do I ensure a proper seal during installation?
Install the cap by hand-tightening it until it feels snug. Overtightening can damage the threads or the seal. After tightening, visually inspect for any gaps and check for fuel odor to ensure a proper seal has been made.
My engine model isn't listed, but the part number matches. Will it fit?
If your old part has the number 878311, this cap should serve as a direct replacement. Our compatibility tables are representative but may not be exhaustive. The part number match is the most reliable indicator of fitment.
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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