Fuel Pump Assembly – Fits Mercury/Tohatsu/Mariner 4-30HP 4-Stroke Outboards (Replaces 803529T04, 3H6-04000-7)
Fuel Pump Assembly – Fits Mercury/Tohatsu/Mariner 4-30HP 4-Stroke Outboards (Replaces 803529T04, 3H6-04000-7) 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).
If you need to return an item, simply login to your account, view the order using the "Complete Orders" link under the My Account menu and click the Return Item(s) button. We'll notify you via e-mail of your refund once we've received and processed the returned item.
Delivery and Shipping
Delivery and Shipping
Free standard shipping on all orders under 1 KG
Fuel Pump Assembly – Fits Mercury/Tohatsu/Mariner 4-30HP 4-Stroke O...
Product Details
This engine-mounted Fuel Pump Assembly – Fits Mercury/Tohatsu/Mariner 4-30HP 4-Stroke Outboards (Replaces 803529T04, 3H6-04000-7) is designed for reliable performance in a range of Mercury, Mariner, Tohatsu, and Nissan 4-Stroke outboards from 4HP to 30HP, covering model years from 2002 to 2016 and up.
It serves as a direct replacement for multiple OEM and aftermarket part numbers, including Mercury 803529A04/803529T04, Tohatsu 3H6-04000-7, and Sierra 18-8865. See the Part Number Matrix for a full list of equivalents.
- Installs directly to the engine block.
- Constructed from durable black plastic for corrosion resistance.
- Designed for use with standard gasoline fuel systems.
Part Number Matrix
Use this matrix to confirm equivalent references across OEM and aftermarket.
| Brand | Part Number |
|---|---|
| Mercury | 803529A04 |
| Mercury | 803529T04 |
| Tohatsu | 3H6-04000-0 |
| Tohatsu | 3H6-04000-1 |
| Tohatsu | 3H6-04000-7 |
| Mariner | 803529T04 |
| Nissan | 3H6040000M |
| Nissan | 3H6040001M |
| Nissan | 3H6040002M |
| Nissan | 3H6040003M |
| Nissan | 3H6040004M |
| Nissan | 3H6040007M |
| Sierra | 18-8865 |
| GLM | 40670 |
Engine & Model Compatibility
Confirm your engine model/year in the table below.
Mercury/Mariner Fitment: This fuel pump is compatible with various 4-stroke models from 5HP to 30HP, including Carb, EFI, and SEAPRO series manufactured from 2003 onwards.
Tohatsu/Nissan Fitment: This part fits a wide range of 4-stroke models from 4HP to 9.8HP, covering years from 2002 through 2014.
| Brand | Model | Rated HP | Stroke | Years | OEM Part No. | Notes |
|---|---|---|---|---|---|---|
| Mercury | 10 Carb (2CYL) | 10 | 4-Stroke | 2003 & Up (0R575531 & Up) | 803529T04 | |
| Mercury | 15 Carb (2CYL) | 15 | 4-Stroke | 2003 & Up (0R235949 & Up) | 803529T04 | |
| Mercury | 15 Carb (2CYL) JCI | 15 | 4-Stroke | 2003 & Up (0R558208 & Up) | 803529T04 | |
| Mercury | 15 SEAPRO | 15 | 4-Stroke | 2003 & Up (0R123565 & Up) | 803529T04 | |
| Mercury | 20 Carb (2CYL) | 20 | 4-Stroke | 2003 & Up (0R235168 & Up) | 803529T04 | |
| Mercury | 25 EFI (3 CYL.) | 25 | 4-Stroke | 2003 & Up (0R106999 & Up) | 803529T04 | |
| Mercury | 25 Jet EFI (3 CYL.) | 25 | 4-Stroke | 2003 & Up (0R165086 & Up) | 803529T04 | |
| Mercury | 30 EFI (3 CYL.) | 30 | 4-Stroke | 2003 & Up (0R106999 & Up) | 803529T04 | |
| Mariner | 4-Stroke | 5 | 4-Stroke | 2003–2016 | 803529T04 | |
| Mariner | 4-Stroke | 6 | 4-Stroke | 2003–2016 | 803529T04 | |
| Tohatsu | MFS4A2 | 4 | 4-Stroke | 2002 | 3H6-04000-7 | |
| Tohatsu | MFS4B | 4 | 4-Stroke | 2005–2010 | 3H6-04000-7 | |
| Tohatsu | MFS4C | 4 | 4-Stroke | 2011–2014 | 3H6-04000-7 | |
| Tohatsu | MFS5A2 | 5 | 4-Stroke | 2002 | 3H6-04000-7 | |
| Tohatsu | MFS5B | 5 | 4-Stroke | 2005–2010 | 3H6-04000-7 | |
| Tohatsu | MFS5C | 5 | 4-Stroke | 2011–2014 | 3H6-04000-7 | |
| Tohatsu | MFS6A2 | 6 | 4-Stroke | 2002 | 3H6-04000-7 | |
| Tohatsu | MFS6B | 6 | 4-Stroke | 2005–2010 | 3H6-04000-7 | |
| Tohatsu | MFS6C | 6 | 4-Stroke | 2011–2014 | 3H6-04000-7 | |
| Tohatsu | MFS8A | 8 | 4-Stroke | 2004 | 3H6-04000-7 | |
| Tohatsu | MFS8A2 | 8 | 4-Stroke | 2004 | 3H6-04000-7 | |
| Tohatsu | MFS8A3 | 8 | 4-Stroke | 2006–2014 | 3H6-04000-7 | |
| Tohatsu | MFS9.8A | 9.8 | 4-Stroke | 2004 | 3H6-04000-7 | |
| Tohatsu | MFS9.8A2 | 9.8 | 4-Stroke | 2004 | 3H6-04000-7 | |
| Tohatsu | MFS9.8A3 | 9.8 | 4-Stroke | 2006–2014 | 3H6-04000-7 | |
| Nissan | NSF4A2 | 4 | 4-Stroke | 2002 | 3H6040007M | |
| Nissan | NSF4B | 4 | 4-Stroke | 2005–2010 | 3H6040007M | |
| Nissan | NSF4C | 4 | 4-Stroke | 2011–2014 | 3H6040007M | |
| Nissan | NSF5A2 | 5 | 4-Stroke | 2002 | 3H6040007M | |
| Nissan | NSF5B | 5 | 4-Stroke | 2005–2010 | 3H6040007M | |
| Nissan | NSF5C | 5 | 4-Stroke | 2011–2014 | 3H6040007M | |
| Nissan | NSF6A2 | 6 | 4-Stroke | 2002 | 3H6040007M | |
| Nissan | NSF6B | 6 | 4-Stroke | 2005–2010 | 3H6040007M | |
| Nissan | NSF6C | 6 | 4-Stroke | 2011–2014 | 3H6040007M | |
| Nissan | NSF8A2 | 8 | 4-Stroke | 2004 | 3H6040007M | |
| Nissan | NSF8A3 | 8 | 4-Stroke | 2006–2014 | 3H6040007M | |
| Nissan | NSF9.8A2 | 9.8 | 4-Stroke | 2004 | 3H6040007M | |
| Nissan | NSF9.8A3 | 9.8 | 4-Stroke | 2006–2014 | 3H6040007M |
Technical Specs
- Product Type
- Mechanical Fuel Pump Assembly
- Installation
- Engine-mounted
- Fuel Type
- Gasoline
- Connection
- Hose Barb
- Housing Material
- Plastic
- Housing Color
- Black
- Height
- 68.4mm (2.69in)
- Weight
- 0.14kg (4.8oz)
- Warranty
- Manufacturer warranty
- Other Technical Attributes
- Top Shaft to Plastic Base: 33.3mm (1.31in)
What’s in the Box
- 1 x Fuel Pump Assembly (803529T04/3H6-04000-7)
Installation Notes
- Disconnect the battery and relieve fuel system pressure according to manufacturer guidelines.
- Place absorbent rags around the old pump to catch any fuel spillage.
- Carefully disconnect the fuel inlet and outlet lines, noting their orientation.
- Remove the mounting bolts securing the old fuel pump to the engine.
- Clean the mounting surface to ensure a proper seal with the new pump.
- Install the new fuel pump assembly, ensuring it is correctly seated. Hand-tighten mounting bolts evenly before torquing to spec.
- Reconnect the fuel lines to the correct barbs on the new pump and secure with clamps.
- Reconnect the battery. Prime the fuel system as per your engine's manual and check thoroughly for leaks before starting the engine.
Troubleshooting & FAQ
How do I know if my fuel pump is failing?
Common signs of a failing mechanical fuel pump include engine sputtering at high speeds, loss of power, difficulty starting, or surging. You may also notice fuel leaking from the pump housing itself. A pressure test can confirm if the pump is delivering fuel within the specified range for your engine.
What is the recommended replacement interval?
There is no fixed replacement interval for this type of mechanical fuel pump. It should be replaced if it fails or shows signs of wear, such as cracks in the housing or leaking seals. Regular inspection during scheduled maintenance is recommended.
Will this pump fit my specific engine model if it's not listed?
If your engine model, year, and serial number range are not explicitly listed in our compatibility table, we cannot guarantee a fit. Please check the part numbers and visual details against your old pump before ordering.
Does this assembly include new gaskets or O-rings?
This package contains the fuel pump assembly as pictured. Gaskets or mounting hardware are not specified as included from our OEM sources. We recommend purchasing new gaskets separately to ensure a leak-free installation.
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
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