Fuel Pump – Fits Mercury/Mariner 4-6 HP & Tohatsu 4-9.8 HP 4-Stroke Engines
Fuel Pump – Fits Mercury/Mariner 4-6 HP & Tohatsu 4-9.8 HP 4-Stroke Engines is backordered and will ship as soon as it is back in stock.
Worry-free returns
Worry-free returns
Shop with confidence. If you’re not completely satisfied, eligible items may be returned within the return window, provided they are unused and in original packaging.
If the return is due to our error or a defective item, we’ll make it right.
Please contact us before returning any item.
Delivery and Shipping
Delivery and Shipping
Orders are typically processed within 1–2 business days.
U.S. orders usually arrive within 6–15 days, depending on stock location and destination.
International delivery times may vary due to customs processing.
Tracking information will be provided once your order ships.
Fuel Pump – Fits Mercury/Mariner 4-6 HP & Tohatsu 4-9.8 HP 4-St...
Fuel Pump – Fits Mercury/Mariner 4-6 HP & Tohatsu 4-9.8 HP 4-Stroke Engines is backordered and will ship as soon as it is back in stock.
Product Details
This replacement Fuel Pump – Fits Mercury/Mariner 4-6 HP & Tohatsu 4-9.8 HP 4-Stroke Engines is engineered to restore reliable fuel delivery to your outboard motor. It is a direct-fit replacement for Mercury/Mariner 4-6 HP 4-Stroke engines (2000–present) and Tohatsu/Nissan MFS/NSF series 4-9.8 HP 4-Stroke engines (2000–present).
This unit serves as a direct interchange for Mercury part numbers 803529T06, 803529T1, 803529T01, 803529T02, and 803529T03, as well as Tohatsu numbers 3H6-04000-7, 3H6-04000-3, 3H6040000M, and 3H6040003M.
- Mechanically driven by the engine's camshaft for consistent performance.
- Features standard barb fittings for simple fuel line connections.
- Constructed from a durable stainless steel and aluminum alloy blend for corrosion resistance.
Part Number Matrix
Use this matrix to confirm equivalent references across OEM and aftermarket.
| Brand | Primary Part Number | Also Replaces |
|---|---|---|
| Mercury/Mariner | 803529T06 | 803529T1, 803529T01, 803529T02, 803529T03 |
| Tohatsu/Nissan | 3H6-04000-7 | 3H6-04000-3, 3H6040000M, 3H6040003M |
Engine & Model Compatibility
Confirm your engine model/year in the table below.
Fits a range of 4-6 HP 4-Stroke Mercury and Mariner outboards manufactured from 2000 to present.
Fits a range of 4-9.8 HP 4-Stroke Tohatsu and Nissan outboards (MFS and NSF series) manufactured from 2000 to present.
| Brand | Model | Rated HP | Stroke | Years | OEM Part No. | Notes |
|---|---|---|---|---|---|---|
| Mercury/Mariner | F4/F5/F6 | 4-6 HP | 4-Stroke | 2000–Present | 803529T06 | Supersedes 803529T1, 803529T02, 803529T03 |
| Tohatsu | MFS4A2, MFS4B | 4 HP | 4-Stroke | 2000–Present | 3H6-04000-7 | Supersedes 3H6-04000-3 |
| Tohatsu | MFS5A2, MFS5B | 5 HP | 4-Stroke | 2000–Present | 3H6-04000-7 | Supersedes 3H6-04000-3 |
| Tohatsu | MFS6A2, MFS6B | 6 HP | 4-Stroke | 2000–Present | 3H6-04000-7 | Supersedes 3H6-04000-3 |
| Tohatsu | MFS8A, MFS8A2, MFS8A3 | 8 HP | 4-Stroke | 2000–Present | 3H6-04000-7 | Supersedes 3H6-04000-3 |
| Tohatsu | MFS9.8A, MFS9.8A2, MFS9.8A3 | 9.8 HP | 4-Stroke | 2000–Present | 3H6-04000-7 | Supersedes 3H6-04000-3 |
| Nissan | NSF4A2, NSF4B | 4 HP | 4-Stroke | 2000–Present | 3H6-04000-7 | Nissan-branded Tohatsu |
| Nissan | NSF5A2, NSF5B | 5 HP | 4-Stroke | 2000–Present | 3H6-04000-7 | Nissan-branded Tohatsu |
| Nissan | NSF6A2, NSF6B | 6 HP | 4-Stroke | 2000–Present | 3H6-04000-7 | Nissan-branded Tohatsu |
| Nissan | NSF8A3 | 8 HP | 4-Stroke | 2000–Present | 3H6-04000-7 | Nissan-branded Tohatsu |
| Nissan | NSF9.8A3 | 9.8 HP | 4-Stroke | 2000–Present | 3H6-04000-7 | Nissan-branded Tohatsu |
Technical Specs
- Product Type
- Mechanical Fuel Pump
- Installation
- Engine-mounted (camshaft-driven)
- Fuel Type
- Gasoline
- Connection
- Barb fittings for fuel line
- Housing Material
- Stainless Steel / Aluminum Alloy
- Housing Color
- Silver/Gray
- Dimensions
- 9.0 x 9.0 x 9.0 cm
- Weight
- Approx. 0.17 kg (0.37 lb)
- Fitting Type
- Barb
- Thread Size
- 0.75 inches (mounting)
- Other Technical Attributes
- Mechanical camshaft-driven pump
- Warranty
- Varies by seller (typically 30-day minimum)
What’s in the Box
- 1 x Fuel Pump (803529T06/3H6-04000-7)
Installation Notes
- Before you begin, disconnect the negative battery cable for safety.
- Carefully relieve any pressure in the fuel system to prevent spills.
- Place a rag under the fuel pump and clamp the fuel lines before disconnecting them. Note their orientation.
- Remove the mounting bolts holding the old fuel pump to the engine block.
- Thoroughly clean the mounting surface, ensuring it is free of old gasket material and debris.
- Position the new fuel pump (with a new gasket, if required) and secure it with the mounting bolts.
- Reconnect the fuel inlet and outlet lines to the correct fittings and secure them with clamps.
- Reconnect the negative battery cable.
- Prime the fuel system according to your engine's manual and check thoroughly for any leaks before starting the engine.
Troubleshooting & FAQ
How do I know if my fuel pump needs to be replaced?
Common signs of a failing fuel pump include engine hesitation, sputtering at high speeds, difficulty starting the engine, a sudden loss of power, or uneven running.
Will this pump fit my specific engine serial number?
This part is designed to fit the engine models and years listed in the compatibility table. While it covers a wide range, we do not have specific data for every engine serial number. Always cross-reference your part number to ensure a correct match.
Is this a difficult part to install?
This pump is a camshaft-driven unit mounted on the engine block. Installation is straightforward for those with mechanical experience but does involve working with the fuel system. Professional installation is always recommended for safety.
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.
Payment & Security
Payment methods
Your payment information is processed securely. We do not store credit card details nor have access to your credit card information.
