Fuel Filter – Fits Mercury Marine 4-85 HP Inline Engines (Replaces 1399-3938)
Fuel Filter – Fits Mercury Marine 4-85 HP Inline Engines (Replaces 1399-3938) 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 Filter – Fits Mercury Marine 4-85 HP Inline Engines (Replaces ...
Product Details
This Fuel Filter – Fits Mercury Marine 4-85 HP Inline Engines (Replaces 1399-3938) is designed for a wide range of Mercury Marine 2-stroke and 4-stroke inline engines from 4 HP to 85 HP, covering various years. It is also compatible with select Johnson/Evinrude models requiring part #0509400.
It directly replaces Mercury parts 1399-3938, 399-39380, 1754, and 3938, as well as Sierra 18-7832 and Johnson/Evinrude 0509400.
- Designed for inline installation on carbureted engines.
- Specifically engineered for use with side bowl carburetors.
Part Number Matrix
Use this matrix to confirm equivalent references across OEM and aftermarket.
| Brand | Part Number |
|---|---|
| Mercury | 1399-3938 |
| Mercury | 399-39380 |
| Mercury | 1754 |
| Mercury | 3938 |
| Sierra | 18-7832 |
| Johnson/Evinrude | 0509400 |
Engine & Model Compatibility
Confirm your engine model/year in the table below.
For Mercury Marine, this filter fits a broad range of 2-stroke models from 4 HP up to 150 HP across various years. Please verify your specific model and OEM part number.
For Johnson/Evinrude, compatibility is based on the OEM part number cross-reference (0509400). Specific models are not detailed; please verify your part number before ordering.
| Brand | Model | Rated HP | Stroke | Years | OEM Part No. | Notes |
|---|---|---|---|---|---|---|
| Mercury | 4 (1 CYL. PRODUCT OF USA) | 4 | 2-Stroke | 1980–1986 | 1399-3938 | |
| Mercury | 4.5 | 4.5 | 2-Stroke | 1975–1986 | 1399-3938 | |
| Mercury | 60 | 6 | 2-Stroke | Various | 1399-3938 | |
| Mercury | 75 | 7.5 | 2-Stroke | Various | 1399-3938 | |
| Mercury | 110 | 9.8 | 2-Stroke | Various | 1399-3938 | |
| Mercury | MARK 10/10A | 10 | 2-Stroke | Various | 1399-3938 | |
| Mercury | MARK 15A | 15 | 2-Stroke | Various | 1399-3938 | |
| Mercury | 200 | 20 | 2-Stroke | Various | 1399-3938 | |
| Mercury | MARK 25/25E | 25 | 2-Stroke | Various | 1399-3938 | |
| Mercury | MARK 28/28A/28AD | 28 | 2-Stroke | Various | 1399-3938 | |
| Mercury | MARK 30H | 30 | 2-Stroke | Various | 1399-3938 | |
| Mercury | 350/MARK 35A | 35 | 2-Stroke | Various | 1399-3938 | |
| Mercury | 400/402 | 40 | 2-Stroke | Various | 1399-3938 | |
| Mercury | 450 | 45 | 2-Stroke | Various | 1399-3938 | |
| Mercury | 500 | 50 | 2-Stroke | 1975–Various | 1399-3938 | |
| Mercury | MARK 55/55E/55H/55AE/55AM | 55 | 2-Stroke | Various | 1399-3938 | |
| Mercury | MARK 58E/58AE | 58 | 2-Stroke | Various | 1399-3938 | |
| Mercury | 600 | 60 | 2-Stroke | Various | 1399-3938 | |
| Mercury | 650 (3 Cyl/4 Cyl) | 65 | 2-Stroke | 1967–1975 | 1399-3938 | |
| Mercury | MARK 75/75A/MARK 78/78A | 75 | 2-Stroke | Various | 1399-3938 | |
| Mercury | 700 | 70 | 2-Stroke | Various | 1399-3938 | |
| Mercury | 800/800 80 | 80 | 2-Stroke | Various | 1399-3938 | |
| Mercury | 850 | 85 | 2-Stroke | 1975 | 1399-3938 | |
| Mercury | 900 | 90 | 2-Stroke | Various | 1399-3938 | |
| Mercury | 950 | 95 | 2-Stroke | Various | 1399-3938 | |
| Mercury | 1000/1000SS/1000BP | 100 | 2-Stroke | Various | 1399-3938 | |
| Mercury | 1100 | 110 | 2-Stroke | Various | 1399-3938 | |
| Mercury | 1150 | 115 | 2-Stroke | 1973–1985 | 1399-3938 | |
| Mercury | 1250/1250BP | 125 | 2-Stroke | Various | 1399-3938 | |
| Mercury | 1350 | 135 | 2-Stroke | Various | 1399-3938 | |
| Mercury | 1400 | 140 | 2-Stroke | Various | 1399-3938 | |
| Mercury | 1500 | 150 | 2-Stroke | 1973–1985 | 1399-3938 | |
| Mercury | 100, 150, 200, 250 | Various | 2-Stroke | Various | 1399-3938 | |
| Mercury | 300 350 | Various | 2-Stroke | Various | 1399-3938 | |
| Johnson/Evinrude | Various Models | Various | 0509400 | Cross-reference provided but specific models not detailed |
Technical Specs
- Product Type
- Inline Fuel Filter
- Installation
- Inline, carbureted engines
- Fuel Type
- Gasoline
- Connection
- Inline
- Dimensions
- 5.56" H x 1.88" W x 1.31" L
- Other Technical Attributes
- For use with side bowl carburetors
What’s in the Box
- 1 x Fuel Filter (1399-3938)
Installation Notes
- Shut off the fuel supply to the engine and place a suitable container underneath the work area to catch any fuel spillage.
- Carefully locate the existing inline fuel filter. Loosen the clamps securing the fuel lines to both ends of the old filter.
- Gently twist and pull the fuel lines off the filter. Be prepared for a small amount of residual fuel to drain out.
- Note the fuel flow direction arrow on the new filter. Install it so the arrow points toward the engine's carburetor.
- Slide the fuel lines onto the new filter and securely fasten the clamps. Ensure they are snug to prevent leaks.
- Turn the fuel supply back on and prime the engine if necessary. Thoroughly inspect the filter and connections for any signs of leaks before starting the engine.
Troubleshooting & FAQ
How do I know if this fuel filter will fit my engine?
This filter is designed for a wide array of Mercury inline engines (4-85+ HP) and select Johnson/Evinrude models. The most reliable way to confirm fitment is to match your existing part number to one of the cross-references: Mercury 1399-3938, Sierra 18-7832, or Johnson/Evinrude 0509400. Also, check the detailed compatibility table for your specific model.
What are the signs of a clogged or failing fuel filter?
Common symptoms include the engine sputtering or bogging down during acceleration, difficulty starting, rough idling, or a noticeable loss of overall power. In some cases, the engine may stall and refuse to restart. Visual inspection might reveal debris inside the filter if it has a clear housing.
What is the recommended replacement interval for this filter?
For optimal engine health and performance, we recommend replacing your inline fuel filter at least once per season or every 100 hours of operation, whichever comes first. Consult your engine’s service manual for manufacturer-specific recommendations.
Is this filter for fuel-injected (EFI) or carbureted engines?
This is an inline filter specifically designed for carbureted engines. It is particularly noted for use with systems that have a side bowl carburetor. It is not suitable for high-pressure fuel-injected (EFI/DFI) systems.
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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