Aftermarket Carburetor for Mercury, Mariner, Tohatsu & Nissan 2–6 HP 4-Stroke Outboards – Replaces 3R1-03200-1, 853720T25
Aftermarket Carburetor for Mercury, Mariner, Tohatsu & Nissan 2–6 HP 4-Stroke Outboards – Replaces 3R1-03200-1, 853720T25 is backordered and will ship as soon as it is back in stock.
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Aftermarket Carburetor for Mercury, Mariner, Tohatsu & Nissan 2...
Aftermarket Carburetor for Mercury, Mariner, Tohatsu & Nissan 2–6 HP 4-Stroke Outboards – Replaces 3R1-03200-1, 853720T25 is backordered and will ship as soon as it is back in stock.
Product Details
This aftermarket carburetor for Mercury, Mariner, Tohatsu, and Nissan 2–6 HP 4-stroke outboards is designed as a replacement for engines that use the applicable part numbers listed below. A properly matched replacement carburetor helps restore consistent fuel delivery, starting performance, idle quality, and throttle response.
This carburetor is listed as an interchange for Mercury part numbers 853720T25 and 803819T03, and for Tohatsu and Nissan references 3R1-03200-1, 3AS-03200-0, and 3GV-03200-0. Confirm the number on your original carburetor and compare the mounting arrangement before ordering.
- Aftermarket replacement for selected small 4-stroke outboard applications.
- Designed for direct replacement where the original part number and configuration match.
- Supports consistent air-and-fuel delivery for normal engine operation.
- Suitable for gasoline-fueled outboard engines within the listed application range.
Part Number Matrix
Use the following references to help compare the replacement with your original carburetor. Part-number matching is recommended because model, production year, serial number, and configuration can affect fitment.
| Brand | Part Number | Reference |
|---|---|---|
| Mercury / Mariner | 853720T25 | Listed replacement reference; also associated with 803819T03. |
| Mercury / Mariner | 803819T03 | Additional replacement reference. |
| Tohatsu / Nissan | 3R1-03200-1 | Listed replacement reference; also associated with 3AS-03200-0 and 3GV-03200-0. |
| Tohatsu / Nissan | 3AS-03200-0 | Additional replacement reference. |
| Tohatsu / Nissan | 3GV-03200-0 | Additional replacement reference. |
Engine & Model Compatibility
This replacement is intended for selected 2–6 HP 4-stroke Mercury, Mariner, Tohatsu, and Nissan outboards. The application examples below are provided as a guide only. Verify the original carburetor part number, mounting pattern, linkage arrangement, fuel connections, and engine identification before purchase.
| Brand | Model or Application | Rated HP | Stroke | Applicable Reference | Fitment Note |
|---|---|---|---|---|---|
| Mercury / Mariner | Selected small outboard applications | 2–6 HP | 4-Stroke | 853720T25 / 803819T03 | Confirm the original part number and configuration. |
| Tohatsu | MF3.5 | 3.5 HP | 4-Stroke | 3R1-03200-1 | Confirm the original part number before ordering. |
| Tohatsu | MFS4 | 4 HP | 4-Stroke | 3R1-03200-1 | Confirm the original part number before ordering. |
| Tohatsu | MFS5 | 5 HP | 4-Stroke | 3R1-03200-1 | Confirm the original part number before ordering. |
| Nissan | NFS4 | 4 HP | 4-Stroke | 3R1-03200-1 | Confirm the original part number before ordering. |
| Nissan | NFS5 | 5 HP | 4-Stroke | 3R1-03200-1 | Confirm the original part number before ordering. |
Important: The table does not establish fitment for every engine in a horsepower or model family. Year, serial-number range, carburetor design, and linkage configuration may vary. Do not use this part on a 2-stroke engine.
Technical Specifications
- Product Type
- Aftermarket carburetor assembly
- Application
- Selected Mercury, Mariner, Tohatsu, and Nissan 2–6 HP 4-stroke outboards
- Fuel Type
- Gasoline
- Installation
- Direct replacement where the original part number and configuration match
- Connection
- Direct-mount replacement design
- Housing Material
- Metal alloy construction
- Housing Color
- Silver/metallic
- Replacement References
- 853720T25, 803819T03, 3R1-03200-1, 3AS-03200-0, and 3GV-03200-0
What’s in the Box
- 1 × Carburetor assembly
Not included: The mounting gasket and any other installation hardware are not included unless specifically shown or stated in the product package. Reuse of an old gasket is not recommended if it is worn, compressed, cracked, or damaged.
Installation Notes
- Turn off the engine, allow it to cool, and follow the applicable service-manual safety procedures. Disconnect the fuel supply before beginning work.
- Remove the engine cowling and document the routing of all hoses, wires, and linkages before removing the original carburetor.
- Disconnect the throttle or choke linkage and fuel hose carefully. Prevent dirt from entering the intake or fuel system.
- Remove the mounting fasteners and old carburetor. Clean the mounting surface without allowing debris to enter the engine.
- Install the replacement using a suitable new gasket if required. Tighten the fasteners evenly to the engine manufacturer’s specified torque.
- Reconnect every hose and linkage in its original position. Confirm that the throttle and choke operate freely without binding.
- Reconnect the fuel supply, prime the system as applicable, and inspect for leaks before starting the engine.
- Start and test the engine in a safe, properly ventilated environment. Follow the manufacturer’s adjustment and break-in procedures if applicable.
Troubleshooting & FAQ
How do I know if my carburetor may need replacement?
Hard starting, unstable idle, stalling, poor acceleration, fuel leakage, or abnormal exhaust smoke can have several causes, including contaminated fuel, restricted passages, ignition problems, or incorrect adjustment. Diagnose the fuel and ignition systems before replacing the carburetor.
Does this carburetor fit a 2-stroke outboard?
No. This listing is for selected 4-stroke applications. It should not be installed on a 2-stroke engine.
How can I confirm fitment?
Compare the number on your original carburetor with the listed references, then compare the mounting points, fuel connections, linkage, and overall appearance. Also verify the engine brand, model, horsepower, stroke, and any available serial-number information.
Does the package include a mounting gasket?
No. The package includes the carburetor assembly only. A suitable mounting gasket should be obtained separately when required.
Will adjustment be required after installation?
Adjustment requirements depend on the engine and the replacement assembly. Follow the engine manufacturer’s service instructions, and do not change mixture or idle settings beyond the manufacturer’s specifications.
What is the difference between an OEM and an aftermarket part?
This is an aftermarket replacement, not an original manufacturer part. Confirm the part number and physical configuration before installation.
How should the fuel system be maintained?
Use clean, fresh fuel, keep water and debris out of the fuel system, follow the engine manufacturer’s storage procedure, and inspect fuel lines and filters regularly. Stabilize or drain fuel as recommended for seasonal storage.
Safety & Important Information
- Verify the original part number and physical configuration before purchase.
- Do not rely on horsepower alone to determine compatibility; model, year, serial range, stroke, and configuration may affect fitment.
- Use the correct gasket and installation torque for your engine.
- Check carefully for fuel leaks before operating the engine.
- Professional installation is recommended if you are unfamiliar with outboard fuel systems.
- This is an aftermarket replacement part, not an OEM component.
About Sea Sierra
- Marine Replacement Parts: We provide replacement components for a range of recreational and commercial marine applications.
- Fitment-Focused Listings: Product references and application information are provided to help customers compare replacement parts with their original components.
- Support: If you are unsure about compatibility, compare your original part and engine identification information before ordering.
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