Fuel Pump Assembly – Fits Tohatsu/Nissan 9.9-30HP (Replaces Tohatsu 3H8-04000-1, Mercury 803529T04)
Fuel Pump Assembly – Fits Tohatsu/Nissan 9.9-30HP (Replaces Tohatsu 3H8-04000-1, Mercury 803529T04) is backordered and will ship as soon as it is back in stock.
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Delivery and Shipping
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Fuel Pump Assembly – Fits Tohatsu/Nissan 9.9-30HP (Replaces Tohatsu...
Fuel Pump Assembly – Fits Tohatsu/Nissan 9.9-30HP (Replaces Tohatsu 3H8-04000-1, Mercury 803529T04) is backordered and will ship as soon as it is back in stock.
Product Details
This Fuel Pump Assembly – Fits Tohatsu/Nissan 9.9-30HP Outboards (Replaces 3H8-04000-1, 803529T04) is designed for a wide range of Tohatsu and Nissan 4-stroke outboard engines, primarily within the MFS and NSF series from 9.9HP to 30HP. It also serves as a cross-reference for certain Mercury outboard applications, ensuring broad compatibility and reliable performance.
It provides a direct interchange for Tohatsu part numbers 3H8-04000-1, 3H8040001, and 3H8040001M, as well as Mercury part numbers 803529T04 and 5041064.
- Engineered for direct OEM replacement, ensuring a precise fit.
- Compatible with standard gasoline, including ethanol-blended fuels.
- Includes all necessary mounting hardware and sealing components for a complete installation.
Part Number Matrix
Use this matrix to confirm equivalent references across OEM and aftermarket.
| Brand | Part Number |
|---|---|
| Tohatsu | 3H8-04000-1 |
| Tohatsu | 3H8040001 |
| Tohatsu | 3H8040001M |
| Mercury | 803529T04 |
| Mercury | 5041064 |
Engine & Model Compatibility
Confirm your engine model/year in the table below.
Fits a variety of Tohatsu and Nissan MFS/NSF series 4-stroke outboards. Verify your specific model against the list.
Also crosses to certain Mercury/Mariner 4-stroke outboards that use the equivalent Tohatsu base engine.
| Brand | Model | Rated HP | Stroke | OEM Part No. | Notes |
|---|---|---|---|---|---|
| Tohatsu | MFS 9.9B2, MFS 9.9C | 9.9 | 4-Stroke | 3H8-04000-1 | |
| Tohatsu | MFS 15B2, MFS 15C | 15 | 4-Stroke | 3H8-04000-1 | |
| Tohatsu | MFS 18B2, MFS 18C | 18 | 4-Stroke | 3H8-04000-1 | |
| Tohatsu | MFS 20 | 20 | 4-Stroke | 3H8-04000-1 | |
| Tohatsu | MFS 25 | 25 | 4-Stroke | 3H8-04000-1 | |
| Tohatsu | MFS 30 | 30 | 4-Stroke | 3H8-04000-1 | |
| Nissan | NSF 9.9B2, NSF 9.9C | 9.9 | 4-Stroke | 3H8-04000-1 | |
| Nissan | NSF 15B2, NSF 15C | 15 | 4-Stroke | 3H8-04000-1 | |
| Nissan | NSF 18B2, NSF 18C | 18 | 4-Stroke | 3H8-04000-1 | |
| Nissan | NSF 20 | 20 | 4-Stroke | 3H8-04000-1 | |
| Nissan | NSF 25 | 25 | 4-Stroke | 3H8-04000-1 | |
| Nissan | NSF 30 | 30 | 4-Stroke | 3H8-04000-1 | |
| Mercury | 4-Stroke | 803529T04 | Cross-reference to Tohatsu 3H8-04000-1 |
Technical Specs
- Product Type
- Fuel Pump Assembly
- Installation
- Direct OEM replacement
- Fuel Type
- Gasoline (including ethanol blends)
- Connection
- OEM fit for Tohatsu/Nissan/Mercury specified models
- Housing Color
- Black
- Weight
- 251g (0.55 lb)
- Fitting Type
- Direct fitment with included hardware
- Warranty
- 1 Year (aftermarket)
- Other Technical Attributes
- Includes mounting hardware and sealing components
What’s in the Box
- 1 x Fuel Pump Assembly (3H8-04000-1/3H8040001/3H8040001M)
- 2 x Hose Clamp (8M0129429) - 9x1mm
- 1 x O-Ring (16109003) - 3x30mm OD
Installation Notes
- Safety First: Work in a well-ventilated area away from open flames or sparks. Disconnect the negative battery terminal before beginning.
- Relieve Fuel Pressure: Locate the fuel pressure relief valve (if equipped) and carefully release system pressure. Have rags ready to catch any fuel spray.
- Disconnect Lines: Place a drain pan under the fuel pump. Carefully disconnect the fuel inlet, outlet, and any vacuum lines connected to the pump. Note their positions.
- Remove Old Pump: Unbolt the old fuel pump assembly from the engine block. Be prepared for some residual fuel to spill.
- Install New Pump: Clean the mounting surface. Install the new O-ring or gasket provided, then mount the new fuel pump assembly, tightening bolts to the manufacturer's recommended torque.
- Reconnect Lines: Securely reconnect all fuel and vacuum lines to their correct ports on the new pump and attach the new hose clamps.
- Final Checks: Reconnect the battery. Prime the fuel system by squeezing the primer bulb until firm. Start the engine and carefully inspect the pump and all connections for leaks.
Troubleshooting & FAQ
How do I know if my fuel pump is failing?
Common signs of a weak or failing fuel pump include difficulty starting the engine (especially when cold), engine bogging down or stalling at speed, sputtering, or a noticeable loss of power under acceleration. A visual inspection may also reveal fuel leaks around the pump body.
Will this fit my specific engine year?
This pump is designed for the Tohatsu and Nissan models listed in the compatibility table. While it covers many years for the MFS/NSF series (9.9-30HP), it is critical to verify your part number. Always compare your original pump to our photos to ensure an exact match before ordering.
What is the main cause of fuel pump failure?
The most common cause of premature fuel pump failure is fuel contamination (dirt, water, or debris) or running the fuel tank empty, which can cause the pump to overheat. Using old or ethanol-heavy fuel can also degrade internal components over time.
Is any special maintenance required for this pump?
No special maintenance is required for the pump itself. However, to ensure its longevity, it's crucial to use clean, fresh fuel and regularly replace your engine's primary fuel filter according to your outboard's service schedule.
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 reliable performance.
Shipping speed & cost
We ship worldwide quickly—typical transit is 5–15 days. Standard shipping is free; expedited options appear at checkout where available.
Warranty & returns
This product is 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 for unused items in their 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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