Carburetor for Mercury/Mariner 2.5–6 HP and Tohatsu/Nissan MFS/NFS 3.5–6 HP 4-Stroke Outboards — Replaces 3R1-03200-1 and 853720T25
Carburetor for Mercury/Mariner 2.5–6 HP and Tohatsu/Nissan MFS/NFS 3.5–6 HP 4-Stroke Outboards — Replaces 3R1-03200-1 and 853720T25 is backordered and will ship as soon as it is back in stock.
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Delivery and Shipping
Delivery and Shipping
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Carburetor for Mercury/Mariner 2.5–6 HP and Tohatsu/Nissan MFS/NFS ...
Carburetor for Mercury/Mariner 2.5–6 HP and Tohatsu/Nissan MFS/NFS 3.5–6 HP 4-Stroke Outboards — Replaces 3R1-03200-1 and 853720T25 is backordered and will ship as soon as it is back in stock.
Product Details
This aftermarket replacement carburetor assembly is designed for selected Mercury and Mariner 4-stroke outboards from 2.5 to 6 HP, as well as selected Tohatsu and Nissan MFS/NFS 4-stroke models from 3.5 to 6 HP. It is intended to restore proper fuel metering and dependable engine operation when the original carburetor is worn, contaminated, damaged, or leaking.
This carburetor is listed as a replacement for several manufacturer part numbers, including Mercury/Mariner 853720T25, 8M0053670, 803522T03, and Tohatsu/Nissan 3R1-03200-1. Confirm the model, horsepower, stroke type, engine serial range, mounting arrangement, and part number of your original carburetor before ordering.
- Direct OEM-style replacement for the listed applications.
- Metal die-cast housing designed for use in marine environments.
- Helps provide the correct air-fuel mixture for starting, idling, acceleration, and normal operation.
- Verify the original part and mounting details before installation; model and year variations may exist.
Part Number Matrix
The following numbers are listed as replacement or reference numbers for this carburetor. They are not the internal product identifier.
| Brand | Part Number |
|---|---|
| Mercury/Mariner | 803522T1 |
| Mercury/Mariner | 803522T2 |
| Mercury/Mariner | 803522T03 |
| Mercury/Mariner | 803522T04 |
| Mercury/Mariner | 803522T05 |
| Mercury/Mariner | 803522T06 |
| Mercury/Mariner | 803522A04 |
| Mercury/Mariner | 8M0053670 |
| Mercury/Mariner | 853720T25 |
| Mercury/Mariner | 898103T51 |
| Mercury/Mariner | 889246T10 |
| Tohatsu/Nissan | 3R1-03200-1 |
| Tohatsu/Nissan | 3R1-03200-1-00 |
| Tohatsu/Nissan | 3AS-03200-0 |
| Tohatsu/Nissan | 3GV-03200-0 |
Engine and Model Compatibility
Use the following applications as a reference. Always compare the engine identification label and the existing carburetor before purchase.
| Brand | Model | Rated HP | Stroke | Reference Part No. |
|---|---|---|---|---|
| Mercury | F2.5/2.5M | 2.5 | 4-Stroke | 853720T25 |
| Mercury | F3.5/3.5M | 3.5 | 4-Stroke | 853720T25 |
| Mercury | F4/4M | 4 | 4-Stroke | 803522T03 |
| Mercury | F5/5M | 5 | 4-Stroke | 803522T03 |
| Mercury | F6/6M | 6 | 4-Stroke | 803522T03 |
Selected Tohatsu and Nissan MFS/NFS 4-stroke outboards in the 3.5–6 HP range are also listed for this replacement. The model and part-number references below should be checked against the engine identification and original component.
| Brand | Model | Rated HP | Stroke | Reference Part No. |
|---|---|---|---|---|
| Tohatsu | MF3.5 | 3.5 | 4-Stroke | 3R1-03200-1 |
| Tohatsu | MFS4 | 4 | 4-Stroke | 3R1-03200-1 |
| Tohatsu | MFS5 | 5 | 4-Stroke | 3R1-03200-1 |
| Nissan | NFS4 | 4 | 4-Stroke | 3R1-03200-1 |
| Nissan | NFS5 | 5 | 4-Stroke | 3R1-03200-1 |
Technical Specifications
- Product Type
- Carburetor assembly
- Application
- Selected 4-stroke marine outboards
- Installation
- Direct replacement
- Fuel Type
- Gasoline
- Connection
- Intake manifold mount
- Housing Material
- Metal, die-cast aluminum
- Housing Color
- Silver/machined
- Fitting Type
- Replacement flange
- Function
- Fuel and air metering for smooth combustion and reliable engine operation
What's in the Box
- 1 x Carburetor assembly
Installation Notes
- Allow the engine to cool, shut off the fuel supply, and follow the engine manufacturer's safety procedures.
- Place an absorbent rag below the carburetor to catch spilled fuel.
- Disconnect the fuel line and any applicable electrical connections.
- Remove the airbox cover and air filter assembly as necessary for access.
- Disconnect the throttle and choke linkages, noting their original positions.
- Remove the fasteners securing the carburetor to the intake manifold.
- Remove the old carburetor without damaging the intake surface or adjacent components.
- Clean the mounting surface and remove old gasket material and debris.
- Install the replacement carburetor with the correct gasket and tighten the fasteners evenly to the manufacturer's specification.
- Reconnect the linkages, fuel line, airbox, and other removed components.
- Turn on the fuel supply, prime the system if required, and inspect carefully for leaks before starting.
- Start and run the engine in a safe, well-ventilated area while checking idle and throttle response.
Troubleshooting and FAQ
How do I confirm fitment?
Compare the engine brand, exact model, horsepower, 4-stroke designation, serial information, mounting arrangement, and original carburetor part number with the information above. A visual comparison of the replacement and original components is also recommended. If any important detail differs, do not install the part without further confirmation.
What are common signs of a failing carburetor?
Symptoms may include hard starting, rough or unstable idle, stalling at low speed, poor acceleration, increased fuel consumption, black exhaust smoke, or fuel leakage around the carburetor.
Will adjustment be required after installation?
This is intended as a direct-fit replacement, but idle speed or mixture adjustment may be required depending on the engine, fuel condition, operating altitude, and installation. Follow the engine manufacturer's adjustment procedure.
How should the carburetor be maintained?
Use fresh fuel and an appropriate stabilizer when required. Inspect fuel lines and connections regularly for deterioration or leaks. For extended storage, follow the engine manufacturer's procedure for draining or stabilizing the fuel system.
Is this an OEM part?
This listing is for an aftermarket replacement carburetor, not an original equipment manufacturer component.
What are the shipping and warranty terms?
Shipping availability, delivery estimates, warranty coverage, and return conditions are determined by the applicable order and store policies. Review the current policy information at checkout or contact support before ordering if these terms are important to your purchase.
Safety and Important Information
- Gasoline is flammable. Work in a well-ventilated area away from ignition sources.
- Verify the engine model, horsepower, stroke type, serial information, and original part before purchase.
- Do not operate the engine if fuel leaks are present.
- Professional installation is recommended when you are not familiar with marine fuel systems.
- This is an aftermarket replacement, not an OEM component.
About Sea Sierra
- Pro-Grade Standards — Marine replacement parts selected for dependable service in real-world conditions.
- Global Fulfillment — Shipping options and delivery estimates are shown according to the destination and current order terms.
- Manufacturer-Direct Value — Practical replacement solutions with attention to fit, materials, and quality control.
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