Aftermarket Fuel Pump Assembly for Mercury/Mariner 4–6 HP 4-Stroke and Tohatsu/Nissan 4–9.8 HP 4-Stroke — Replaces 803529T06 and 3H6-04000-7
Aftermarket Fuel Pump Assembly for Mercury/Mariner 4–6 HP 4-Stroke and Tohatsu/Nissan 4–9.8 HP 4-Stroke — Replaces 803529T06 and 3H6-04000-7 is backordered and will ship as soon as it is back in stock.
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Delivery and Shipping
Delivery and Shipping
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Aftermarket Fuel Pump Assembly for Mercury/Mariner 4–6 HP 4-Stroke ...
Aftermarket Fuel Pump Assembly for Mercury/Mariner 4–6 HP 4-Stroke and Tohatsu/Nissan 4–9.8 HP 4-Stroke — Replaces 803529T06 and 3H6-04000-7 is backordered and will ship as soon as it is back in stock.
Product Details
This aftermarket mechanical fuel pump assembly is designed for selected Mercury and Mariner 4–6 HP 4-stroke outboard engines and selected Tohatsu and Nissan 4–9.8 HP 4-stroke outboards. It replaces specified fuel pump references including Mercury/Mariner 803529T06 and Tohatsu/Nissan 3H6-04000-7.
The pump is supplied as a single fuel pump assembly. It is not an OEM-branded component. Always compare the part number, engine model, horsepower, stroke, and serial-number range before ordering.
- Aftermarket mechanical fuel pump assembly.
- For selected 4-stroke outboard fuel systems.
- One complete fuel pump assembly included.
- Replaces the applicable OEM references listed below.
Part Number Matrix
The following numbers are manufacturer or aftermarket reference numbers associated with this replacement application. Confirm your original pump and engine application before purchase.
| Brand | Part Number | Reference |
|---|---|---|
| Mercury/Mariner | 803529T06 | Primary replacement reference |
| Mercury/Mariner | 803529T1 | Earlier reference |
| Mercury/Mariner | 803529T02 | Earlier reference |
| Mercury/Mariner | 803529T03 | Earlier reference |
| Tohatsu/Nissan | 3H6-04000-7 | Primary replacement reference |
| Tohatsu/Nissan | 3H6-04000-3 | Earlier reference |
| Tohatsu/Nissan | 3H6-04000-1, 3H6-04000-2, 3H6-04000-4 | Additional earlier references |
| Tohatsu/Nissan | 3H6040007M | Reference number |
Engine & Model Compatibility
Compatibility depends on the complete engine application. Match the brand, horsepower, 4-stroke configuration, model designation, and—where applicable—the serial-number range.
Tohatsu and Nissan 4-Stroke Models
| Brand | Model | Rated HP | Stroke | Reference |
|---|---|---|---|---|
| Tohatsu/Nissan | MFS4A2, MFS4B | 4 | 4-Stroke | 3H6-04000-7 |
| Tohatsu/Nissan | MFS5A2, MFS5B | 5 | 4-Stroke | 3H6-04000-7 |
| Tohatsu/Nissan | MFS6A2, MFS6B | 6 | 4-Stroke | 3H6-04000-7 |
| Tohatsu/Nissan | MFS8A, MFS8A2, MFS8A3 | 8 | 4-Stroke | 3H6-04000-7 |
| Tohatsu/Nissan | MFS9.8A, MFS9.8A2, MFS9.8A3 | 9.8 | 4-Stroke | 3H6-04000-7 |
Catalog applications also list the 3H6-04000-7 fuel pump assembly on later Tohatsu MFS4/MFS5/MFS6 and MFS6/MFS8/MFS9.8 model families. Verify the exact model designation and parts diagram for your engine.
Mercury and Mariner 4-Stroke Models
| Brand | Rated HP | Stroke | Serial-number condition | Reference |
|---|---|---|---|---|
| Mercury/Mariner | 4 | 4-Stroke | Application-specific; catalog listings include 0P073456–0P400999 and 0R000001–0R411837 ranges | 803529T06 |
| Mercury/Mariner | 5 | 4-Stroke | Application-specific; catalog listings include 0P073456–0P400999, 0R000001–0R411837, and 0R560794 and up | 803529T06 |
| Mercury/Mariner | 6 | 4-Stroke | Application-specific; catalog listings include 0P073456–0P400999 and 0R000001–0R411837 ranges | 803529T06 |
Technical Specifications
- Product Type
- Mechanical fuel pump assembly
- Application
- Selected Mercury/Mariner and Tohatsu/Nissan 4-stroke outboard fuel systems
- Fuel Type
- Gasoline
- Replacement References
- 803529T06 and 3H6-04000-7, plus the related references listed above
- Product Status
- Aftermarket replacement; not an OEM-branded component
What's in the Box
- 1 x Fuel pump assembly
Gaskets, hoses, filters, mounting hardware, and other components are not included unless specifically shown or stated in the order details.
Installation Notes
- Work in a well-ventilated area away from open flames, sparks, and ignition sources.
- Stop the engine, allow it to cool, and disconnect the battery where applicable.
- Relieve fuel-system pressure and place an absorbent cloth beneath the fuel connections.
- Mark the inlet and outlet hose positions before disconnecting the existing pump.
- Remove the old pump and clean the mounting surface without damaging the engine or sealing surface.
- Install the replacement pump using the correct gasket or seal for your engine. Do not reuse a damaged gasket.
- Reconnect the fuel lines in their original positions and secure them properly.
- Prime the fuel system according to the engine manufacturer's service instructions.
- Inspect all connections for leaks before starting the engine, then recheck for leaks after startup.
Follow the service manual for your exact engine when tightening fasteners or servicing the fuel system. If you are unsure about the application or installation, use a qualified marine technician.
Troubleshooting & FAQ
How do I confirm that this fuel pump fits my engine?
Compare the existing pump's manufacturer number with the references in the Part Number Matrix. Then confirm the engine brand, model, horsepower, 4-stroke configuration, and serial-number range where applicable. A horsepower match alone does not confirm compatibility.
What symptoms can indicate a fuel-pump problem?
Possible symptoms include hard starting, stalling, hesitation, loss of power, or insufficient fuel delivery. These symptoms can also be caused by clogged filters, restricted hoses, carburetor problems, air leaks, or ignition faults, so diagnose the complete fuel system before replacing the pump.
Is this an OEM fuel pump?
No. This listing is for an aftermarket replacement assembly intended for the applications and reference numbers shown on this page.
Does the package include a fuel filter?
No. This product is a single fuel pump assembly. A fuel filter or other accessories are not included unless separately stated in the order details.
Does the pump require special maintenance?
The pump itself is not normally serviced as a routine maintenance item. Use clean, fresh fuel and follow the engine manufacturer's recommendations for fuel-filter replacement and fuel-system maintenance.
What should I do if the part looks different from my original?
Do not install it until the part number, mounting arrangement, hose connections, and engine application have been verified. Contact a qualified technician or compare the engine's official parts diagram before proceeding.
Safety & Important Information
- Verify the complete application before purchase; model, horsepower, stroke, and serial-number conditions must be considered together.
- This is an aftermarket replacement part and is not manufactured or branded by Mercury, Mariner, Tohatsu, or Nissan.
- Fuel-system work involves flammable materials. Use proper ventilation and follow the engine manufacturer's safety procedures.
- Professional installation is recommended if you are not experienced with marine fuel systems.
About Sea Sierra
- Marine Replacement Parts — We provide replacement components for common outboard service applications.
- Application-Focused Listings — Product pages identify reference numbers and fitment conditions to support accurate part selection.
- Support When Needed — Compare your original part and engine identification details before installation, and contact support if application information is unclear.
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