Carburetor Assembly – Fits Tohatsu & Nissan 2.5HP & 3.5HP 2-Stroke and Mercury 2HP, 2.2HP, 2.5HP, 3HP & 3.3HP (Replaces 3F0-03100-4, 823040A1)

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Carburetor Assembly – Fits Tohatsu & Nissan 2.5HP & 3.5HP 2-Stroke and Mercury 2HP, 2.2HP, 2.5HP, 3HP & 3.3HP (Replaces 3F0-03100-4, 823040A1) is backordered and will ship as soon as it is back in stock.

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Product Details

This Carburetor Assembly – Fits Tohatsu & Nissan 2.5HP & 3.5HP 2-Stroke and Mercury 2HP, 2.2HP, 2.5HP, 3HP & 3.3HP (Replaces 3F0-03100-4, 823040A1) is designed for Tohatsu and Nissan 2-stroke outboard motors (2.5HP/3.5HP) from 2002 to 2005. It also fits a range of Mercury and Mariner 1-cylinder 2-stroke engines, including 2HP, 2.2HP, 2.5HP, 3HP, and 3.3HP models, identified by specific serial number ranges.

It provides a direct interchange for Tohatsu, Nissan, and Mercury part numbers, including 3F0-03100-4, 3D5-03100-5, and 823040A1 among others, ensuring a precise fit for listed models.

Installs as a direct replacement for the original OEM carburetor.
Features marine-grade, corrosion-resistant construction for durability.
Includes one complete carburetor assembly for a straightforward swap.

Part Number Matrix

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

Brand	Part Number
Tohatsu / Nissan	3F0-03100-4
Tohatsu / Nissan	3F0-03100-3
Tohatsu / Nissan	3F0-03100-2
Tohatsu / Nissan	3F0-03100-1
Tohatsu / Nissan	3F0-03100-0
Tohatsu / Nissan	3D5-03100-5
Tohatsu / Nissan	3D5-03100-4
Tohatsu / Nissan	3D5-03100-3
Tohatsu / Nissan	3D5-03100-2
Tohatsu / Nissan	3F0031003M
Tohatsu / Nissan	3F0031002M
Tohatsu / Nissan	3F0031001M
Tohatsu / Nissan	3F0031000M
Mercury	823040A1
Mercury	823040A2
Mercury	823040A4
Mercury	823040A5
Mercury	823040T06
Mercury	8M0171810
Mercury	3303-8231752
Mercury	3303-815070

Engine & Model Compatibility

Confirm your engine model/year in the table below.

Tohatsu Models: Fits various M2.5 and M3.5 models from 2002 through 2005.

Brand	Model	Rated HP	Stroke	Years	OEM Part No.
Tohatsu	M3.5A2	3.5	2-Stroke	2002 & Earlier	3F0-03100-4
Tohatsu	M3.5B2	3.5	2-Stroke	2002 & Earlier	3F0-03100-4
Tohatsu	M3.5A2	3.5	2-Stroke	2003	3F0-03100-4
Tohatsu	M3.5B2	3.5	2-Stroke	2003	3F0-03100-4
Tohatsu	M3.5A2	3.5	2-Stroke	2004	3F0-03100-4
Tohatsu	M3.5B2	3.5	2-Stroke	2004	3F0-03100-4
Tohatsu	M3.5A2	3.5	2-Stroke	2005	3F0-03100-4
Tohatsu	M3.5B2	3.5	2-Stroke	2005	3F0-03100-4
Tohatsu	M2.5A2	2.5	2-Stroke	2002–2005	3F0-03100-4

Nissan Models: Fits various NS2.5 and NS3.5 models from 2002 through 2005.

Brand	Model	Rated HP	Stroke	Years	OEM Part No.
Nissan	NS3.5B2	3.5	2-Stroke	2002 & Earlier	3F0-03100-4
Nissan	NS3.5A2	3.5	2-Stroke	2003	3F0-03100-4
Nissan	NS3.5B2	3.5	2-Stroke	2003	3F0-03100-4
Nissan	NS3.5A2	3.5	2-Stroke	2004	3F0-03100-4
Nissan	NS3.5B2	3.5	2-Stroke	2004	3F0-03100-4
Nissan	NS3.5A2	3.5	2-Stroke	2005	3F0-03100-4
Nissan	NS3.5B2	3.5	2-Stroke	2005	3F0-03100-4
Nissan	NS2.5A2	2.5	2-Stroke	2002–2005	3F0-03100-4

Mercury / Mariner Models: Compatibility is determined by HP rating and serial number range. Please verify your engine's serial number before ordering.

Brand	Rated HP	Stroke	OEM Part No.	Notes
Mercury	2.5	2-Stroke	823040A1	Serial number: 017000+
Mercury	3	2-Stroke	823040A1	Serial number: 0A855097 to 0G710612
Mercury	3.3	2-Stroke	823040A1	Serial number: 0D901217+

Technical Specs

Product Type: Carburetor Assembly
Installation: Direct Replacement
Fuel Type: Gasoline
Housing Material: Zinc Alloy
Housing Color: Silver
Other Technical Attributes: Marine-grade corrosion resistant construction

What’s in the Box

1 x Carburetor Assembly (3F0-03100-4/3D5-03100/823040A1)

Installation Notes

Safety First: Disconnect the battery terminals and ensure the engine is off and cool. Shut off the fuel supply.
Disconnect Lines: Carefully disconnect the fuel lines and any throttle linkages connected to the old carburetor. Note their positions for reassembly.
Remove Old Carburetor: Unscrew the mounting bolts holding the carburetor to the intake manifold. Remove the old unit and gasket.
Clean Surface: Clean the manifold mounting surface to ensure a proper seal with the new gasket.
Install New Carburetor: Position the new gasket and carburetor, then tighten the mounting bolts evenly.
Reconnect Lines: Re-attach the fuel lines and throttle linkages to their original positions.
Final Checks: Turn the fuel supply back on and check for any leaks. Reconnect the battery.
Test: Start the engine and let it warm up. Adjust idle settings if necessary according to your engine's service manual.

Troubleshooting & FAQ

How do I know if this carburetor fits my engine?

The best way to confirm fitment is to check your original part number against the list in our Part Number Matrix. For Mercury models, you must also verify your engine’s serial number falls within the specified ranges. Visually comparing the new part to your old one is always recommended.

What are the signs of a failing carburetor?

Common symptoms include difficulty starting, rough idling, engine stalling at low speeds, black smoke from the exhaust, and poor fuel economy. If you notice any of these issues, your carburetor may need servicing or replacement.

Is any adjustment needed after installation?

This carburetor is designed as a direct-fit replacement and should work out of the box for most compatible models. However, minor idle speed or air/fuel mixture adjustments may be necessary depending on your specific engine and local conditions. Refer to your engine’s service manual for guidance.

What is the recommended maintenance for this carburetor?

To ensure long life, use clean, fresh fuel and a fuel stabilizer during storage. Regularly check and clean the fuel filter. If the engine will be stored for an extended period, it's best to drain the carburetor bowl to prevent gum and varnish buildup.

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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