SeaSierra Outboard Fuel Pump for Mercury 4–6 HP & Tohatsu/Nissan 4–9.8 HP — Direct-Fit 803529T06 Replacement

The SeaSierra 803529T06 outboard fuel pump is a direct-fit replacement assembly that restores fuel delivery for Mercury, Tohatsu, and Nissan 4–9.8 HP 4-stroke outboards.

This replacement fuel pump assembly is engineered to match the internal components of original equipment so small outboard motors regain proper fuel flow and reliable starting. Built for owners and technicians who need a drop-in spare or service part, the SeaSierra unit aligns with multiple OEM numbers and common 4–9.8 HP models across Mercury/Mariner, Tohatsu, and Nissan lines. The material selection and dimensional compatibility make it suitable for routine maintenance and emergency repairs on older or modern small outboards.

Which outboard models does this pump fit?

The SeaSierra 803529T06 is designed for specific 4-stroke small outboard engines from several manufacturers. It matches factory dimensions and mounting points used across model years so it can replace worn internal pump components without modification.

• Mercury/Mariner 4HP, 5HP, 6HP 4-stroke outboards
• Tohatsu 4hp–9.8hp MFS series including MFS4, MFS5, MFS6, MFS8, MFS9.8 variants
• Nissan/NSF 4hp–9.8hp 4-stroke NSF series engines
• Cross-references common OEM part numbers for straightforward replacement

How do I know this replaces my OEM part number?

SeaSierra provides cross-reference compatibility so you can confirm fitment against OEM references before purchase. The listing cites several factory part numbers that this unit is intended to replace, simplifying comparison with the number stamped on your original pump or parts diagram.

• Cross-references include Tohatsu OEM numbers such as 3H6-04000 series
• Matches Mercury/Mariner references including 803529T06, 803529T03 and related codes
• Compare your existing component number to the listed references to verify compatibility

What should I expect during installation and performance?

Installation is typically straightforward for someone familiar with small outboard maintenance: remove the lower fuel pump assembly, swap the internal components, and reassemble using original fasteners and gaskets. Once installed, you should notice restored fuel suction and more consistent starting when the pump was the cause of fuel delivery issues.

• Designed to fit factory housings and mounting points for a direct swap
• Installation usually requires basic hand tools and adherence to service manual steps
• Inspect hoses and seals while replacing the pump to ensure a leak-free system

What materials and quality controls are used?

SeaSierra selects durable materials for the moving parts and diaphragms used in the fuel pump assembly to resist fuel degradation and wear. While not an OEM-manufactured unit, this replacement is produced to meet dimensional tolerances and functional requirements expected in routine marine service.

• Durable diaphragm material suited for modern gasoline blends
• Precision-molded components to match OEM fit and function
• Quality checks for dimensional accuracy and flow characteristics

Who is this for: The SeaSierra 803529T06 fuel pump assembly is aimed at boat owners, marine technicians, and repair shops maintaining small outboard engines from Mercury/Mariner, Tohatsu, and Nissan. If you need a cost-effective aftermarket replacement that cross-references common OEM numbers and restores fuel delivery on 4–9.8 HP 4-stroke outboards, this unit is a practical service part to carry or install during routine engine maintenance.