Carburetor – Fits Mercury/Mariner 2–6 HP & Tohatsu/Nissan MFS/NFS 3.5–6 HP 4-Stroke Outboards (Replaces 3R1-03200-1, 853720T25)

$33.99 $54.00

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Carburetor – Fits Mercury/Mariner 2–6 HP & Tohatsu/Nissan MFS/NFS 3.5–6 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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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).

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Delivery and Shipping

Free standard shipping on all orders under 1 KG

If you have any questions, feel free to email us at info@sierramarines.com, and we’ll get back to you within 20–36 hours.

Product Details

This is a replacement Carburetor – Fits Mercury/Mariner 2–6 HP & Tohatsu/Nissan MFS/NFS 3.5–6 HP 4-Stroke Outboards, designed for reliable performance in a wide range of engines. It is compatible with various Mercury/Mariner 2–6 HP 4-stroke models from the early 2000s to the present, as well as Tohatsu and Nissan 3.5–6 HP 4-stroke outboards from the MFS/NFS series manufactured since the early 2000s.

It serves as a direct interchange for numerous OEM part numbers, including Mercury 853720T25, 8M0053670, and Tohatsu 3R1-03200-1, ensuring broad compatibility.

Installs as a direct OEM-style replacement without modification.
Constructed from durable, die-cast aluminum for longevity in marine environments.
Engineered to provide a precise air-fuel mixture for smooth combustion and efficient engine operation.

Part Number Matrix

Use this matrix to confirm equivalent references across OEM and aftermarket.

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 & Model Compatibility

Confirm your engine model/year in the table below.

This carburetor fits a range of Mercury and Mariner 4-stroke outboard models from 2.5 to 6 HP.

Brand	Model	Rated HP	Stroke	OEM 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

Compatible with various Tohatsu and Nissan 4-stroke outboards, including the MFS and NFS series from 3.5 to 5 HP.

Brand	Model	Rated HP	Stroke	OEM 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 Specs

Product Type: Carburetor Assembly
Installation: Direct Replacement
Fuel Type: Gasoline
Connection: Intake Manifold Mount
Housing Material: Metal (Die-cast aluminum)
Housing Color: Silver/Machined
Fitting Type: Replacement Flange
Other Technical Attributes: OEM-compatible carburetor providing precise air-fuel mixture for smooth combustion and reliable operation

What’s in the Box

1 x Carburetor Assembly (3R1-03200-1/853720T25/803522T03)

Installation Notes

Ensure the engine is cool. Disconnect the negative battery terminal and shut off the fuel supply valve.
Place a rag below the carburetor to catch any spilled fuel.
Carefully disconnect the fuel line(s) from the carburetor.
Remove the airbox cover and air filter assembly to access the carburetor.
Disconnect the throttle linkage and choke linkage (if applicable). Note their positions for reassembly.
Remove the nuts or bolts securing the carburetor to the intake manifold studs.
Gently pull the carburetor off, being careful not to damage the old gasket.
Clean the intake manifold mounting surface thoroughly, removing any old gasket material or debris.
Position the new gasket and carburetor onto the mounting studs.
Tighten the mounting nuts or bolts evenly to the manufacturer's recommended torque. Do not overtighten.
Reconnect all linkages, fuel lines, and any other connections. Reinstall the airbox assembly.
Turn the fuel supply on, prime if necessary, and check for leaks before starting the engine.

Troubleshooting & FAQ

How do I know if this carburetor fits my specific outboard model?

Check your engine's model, horsepower, and stroke type. Compare your existing carburetor's part number against the comprehensive list of direct replacements provided in our Part Number Matrix. When in doubt, a visual comparison between your old part and our product images is the most reliable method.

What are the signs my old carburetor is failing?

Common symptoms include difficulty starting (hard starts), rough or erratic idling, stalling at low speeds, poor acceleration, increased fuel consumption, or black smoke from the exhaust. Fuel leaks around the carburetor body are also a clear sign of failure.

Is any adjustment needed after installation?

This carburetor is designed as a direct-fit replacement and is often ready to use out of the box. However, minor adjustments to the idle speed or air-fuel mixture screw may be necessary to achieve optimal performance based on your specific engine's condition and local altitude.

What is the recommended maintenance for this carburetor?

To ensure longevity, always use high-quality, fresh fuel with a stabilizer, especially if the engine is used infrequently. Periodically check that all connections are secure and free of leaks. For long-term or winter storage, it is recommended to drain the fuel from the carburetor bowl to prevent gumming and deposits.

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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