Fuel Pump – Fits Mercury Marine 4-6 HP & Tohatsu Nissan 4-9.8 HP (Replaces 803529T01, 803529T02, 803529T06)
Fuel Pump – Fits Mercury Marine 4-6 HP & Tohatsu Nissan 4-9.8 HP (Replaces 803529T01, 803529T02, 803529T06) is backordered and will ship as soon as it is back in stock.
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Worry-free returns
Worry-free returns
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
Delivery and Shipping
Free standard shipping on all orders under 1 KG
Fuel Pump – Fits Mercury Marine 4-6 HP & Tohatsu Nissan 4-9.8 H...
Product Details
This aftermarket Fuel Pump – Fits Mercury Marine 4-6 HP & Tohatsu Nissan 4-9.8 HP is engineered for a precise fit on select 4-Stroke outboard engines. It is designed for Mercury Marine 4-6 HP outboards and Tohatsu/Nissan's MFS/NSF series 4-9.8 HP four-stroke models, ensuring reliable fuel delivery for optimal engine performance.
This component serves as a direct replacement for Mercury part numbers 803529T, 803529T01, 803529T02, 803529T03, 803529T06, and Tohatsu/Nissan equivalents 3H6-04000-0, 3H6-04000-1, 3H6-04000-2, 3H6-04000-3, 3H6-04000-4, 3H6-04000-5, 3H6-04000-6, and 3H6-04000-7.
- Mechanically activated by the engine camshaft.
- Engine-specific fit ensures straightforward installation.
- Kit includes the fuel pump, O-ring, and installation clamps.
Part Number Matrix
Use this matrix to confirm equivalent references across OEM and aftermarket suppliers.
| Brand | Part Number |
|---|---|
| Mercury Marine | 803529T |
| Mercury Marine | 803529T01 |
| Mercury Marine | 803529T02 |
| Mercury Marine | 803529T03 |
| Mercury Marine | 803529T06 |
| Tohatsu / Nissan | 3H6-04000-0 |
| Tohatsu / Nissan | 3H6-04000-1 |
| Tohatsu / Nissan | 3H6-04000-2 |
| Tohatsu / Nissan | 3H6-04000-3 |
| Tohatsu / Nissan | 3H6-04000-4 |
| Tohatsu / Nissan | 3H6-04000-5 |
| Tohatsu / Nissan | 3H6-04000-6 |
| Tohatsu / Nissan | 3H6-04000-7 |
Engine & Model Compatibility
Confirm your engine model/year in the table below.
For Mercury Marine engines, this pump fits 4, 5, and 6 HP 4-Stroke models.
| Brand | Model | Rated HP | Stroke | OEM Part No. | Notes |
|---|---|---|---|---|---|
| Mercury | 4 HP Carb | 4 | 4-Stroke | 803529T, 803529T01, 803529T02, 803529T03, 803529T06 | |
| Mercury | 5 HP Carb | 5 | 4-Stroke | 803529T, 803529T01, 803529T02, 803529T03, 803529T06 | Including 5 HP Carb JCI model |
| Mercury | 6 HP Carb | 6 | 4-Stroke | 803529T, 803529T01, 803529T02, 803529T03, 803529T06 |
For Tohatsu and Nissan outboards, this pump fits a wide range of MFS and NSF 4-Stroke models from 4 HP to 9.8 HP.
| Brand | Model | Rated HP | Stroke | OEM Part No. | Notes |
|---|---|---|---|---|---|
| Tohatsu | MFS4A2, MFS4B, MFS4C | 4 | 4-Stroke | 3H6-04000-0, 3H6-04000-1, 3H6-04000-2, 3H6-04000-3, 3H6-04000-4, 3H6-04000-5, 3H6-04000-6, 3H6-04000-7 | |
| Nissan | NSF4A2, NSF4B, NSF4C | 4 | 4-Stroke | 3H6-04000-0, 3H6-04000-1, 3H6-04000-2, 3H6-04000-3, 3H6-04000-4, 3H6-04000-5, 3H6-04000-6, 3H6-04000-7 | |
| Tohatsu | MFS5A2, MFS5B, MFS5C | 5 | 4-Stroke | 3H6-04000-0, 3H6-04000-1, 3H6-04000-2, 3H6-04000-3, 3H6-04000-4, 3H6-04000-5, 3H6-04000-6, 3H6-04000-7 | |
| Nissan | NSF5A2, NSF5B, NSF5C | 5 | 4-Stroke | 3H6-04000-0, 3H6-04000-1, 3H6-04000-2, 3H6-04000-3, 3H6-04000-4, 3H6-04000-5, 3H6-04000-6, 3H6-04000-7 | |
| Tohatsu | MFS6A2, MFS6B, MFS6C | 6 | 4-Stroke | 3H6-04000-0, 3H6-04000-1, 3H6-04000-2, 3H6-04000-3, 3H6-04000-4, 3H6-04000-5, 3H6-04000-6, 3H6-04000-7 | |
| Nissan | NSF6A2, NSF6B, NSF6C | 6 | 4-Stroke | 3H6-04000-0, 3H6-04000-1, 3H6-04000-2, 3H6-04000-3, 3H6-04000-4, 3H6-04000-5, 3H6-04000-6, 3H6-04000-7 | |
| Tohatsu | MFS8A2, MFS8A3 | 8 | 4-Stroke | 3H6-04000-0, 3H6-04000-1, 3H6-04000-2, 3H6-04000-3, 3H6-04000-4, 3H6-04000-5, 3H6-04000-6, 3H6-04000-7 | |
| Nissan | NSF8A2, NSF8A3 | 8 | 4-Stroke | 3H6-04000-0, 3H6-04000-1, 3H6-04000-2, 3H6-04000-3, 3H6-04000-4, 3H6-04000-5, 3H6-04000-6, 3H6-04000-7 | |
| Tohatsu | MFS9.8A2, MFS9.8A3 | 9.8 | 4-Stroke | 3H6-04000-0, 3H6-04000-1, 3H6-04000-2, 3H6-04000-3, 3H6-04000-4, 3H6-04000-5, 3H6-04000-6, 3H6-04000-7 | |
| Nissan | NSF9.8A2, NSF9.8A3 | 9.8 | 4-Stroke | 3H6-04000-0, 3H6-04000-1, 3H6-04000-2, 3H6-04000-3, 3H6-04000-4, 3H6-04000-5, 3H6-04000-6, 3H6-04000-7 |
Technical Specs
- Product Type
- Marine Outboard Fuel Pump
- Installation
- Vehicle/Engine-specific fit
- Fuel Type
- Gasoline
- Connection
- Hose Barb Input, Screw Output
- Housing Material
- Marine Grade Fuel Pump (exact material not specified)
- Housing Color
- Silver/Metallic
- Dimensions
- 114.5 × 91 × 62 mm (4.53 × 3.58 × 2.44 inches) [package dimensions]
- Weight
- 0.18 kg (6.4 ounces)
- Fitting Type
- Transom Mount
- Thread Size
- 0.25 inches (connection size)
- Other Technical Attributes
- Mechanical pump (activated by engine camshaft)
What’s in the Box
- 1 x Fuel pump (803529T01/3H6-04000-1)
- 2 x Clamps/clips (54-95395)
- 1 x O-ring (25-803513)
Installation Notes
- Disconnect the negative battery terminal to prevent accidental shorts.
- Carefully relieve any pressure in the fuel system according to the engine service manual.
- Place absorbent rags under the fuel line connections to catch any spillage.
- Disconnect the fuel inlet and outlet lines from the old pump. Note their orientation.
- Unbolt and remove the old fuel pump from the engine block.
- Clean the mounting surface and install the new O-ring provided.
- Mount the new fuel pump, ensuring it is correctly seated, and tighten the mounting bolts to the specified torque.
- Reconnect the fuel lines to the correct ports on the new pump and secure with the new clamps.
- Reconnect the battery terminal.
- Prime the fuel system if required by your engine model, and check thoroughly for any leaks before starting the engine.
Troubleshooting & FAQ
How do I know if this fuel pump fits my engine?
The best way to ensure compatibility is to verify your engine's model and horsepower against the lists in the Engine & Model Compatibility section. Additionally, cross-reference your existing part number with those listed in our Part Number Matrix.
What are the signs of a failing fuel pump?
Common symptoms include the engine sputtering or bogging down at high speeds, difficulty starting, rough idling, or a complete failure to start. Loss of power during acceleration is another strong indicator.
Is this a mechanical or electric pump?
This is a mechanical fuel pump. It is actuated by a lobe on the engine's camshaft, which means it does not require an electrical connection.
What is the difference between the 'T' numbers (e.g., T01, T02, T06)?
These suffixes (T01, T02, etc.) typically denote minor revisions, design updates, or supersessions from the original manufacturer over time. All listed variations are interchangeable and will function identically for the specified applications.
OEM vs. Aftermarket?
This listing is an aftermarket replacement (not OEM). It is built to OEM-level specifications with comparable materials. Manufactured in an ISO 9002 facility, it is batch-inspected for consistency and reliability.
Shipping speed & cost?
We ship worldwide quickly—typical transit is 5–15 days. Standard shipping is free for most orders; expedited options will appear at checkout where available for your region.
Warranty & returns?
This product is covered by a 1-year warranty against manufacturing defects under normal marine use. If you encounter any issues, please contact our support team with your order details. Returns are accepted within our standard window, provided the item is unused and in its original packaging. Please see our full policy page or reach out for instructions.
Safety & Important Info
- Verify images and specifications against your original part. If anything differs—even if your model appears compatible—do not purchase.
- This is an aftermarket replacement part, not an original equipment manufacturer (OEM) component.
- Professional installation is highly recommended for safety and to ensure proper performance.
About Sea Sierra
- Pro-Grade Standards — We supply marine parts engineered to OEM-level tolerances and rigorously tested for real-world conditions.
- Fast Global Fulfillment — We offer free standard delivery to most regions, with typical transit times of just 5–15 days.
- Manufacturer-Direct Value — By working directly with our manufacturing partners, we provide fair pricing without compromising on materials or quality control.
Payment & Security
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