Aftermarket Mercury Fuel Pump Kit 857005A1 Sierra 18-7817

Aftermarket diaphragm repair kit for compatible square-style fuel pumps used on selected Mercury, Mariner and Force outboards. It replaces Mercury/Quicksilver 857005A1 and Sierra 18-7817; identify the fitted pump before ordering.

Key Features

• Aftermarket fuel-pump diaphragm repair kit
• Includes diaphragms, gaskets and small service components shown
• For compatible square-style mechanical fuel pumps
• Rebuilds the serviceable pump rather than replacing the complete assembly

Technical Specs

• Product type: fuel-pump repair kit
• Fuel-pump type: mechanical diaphragm pump
• Application: selected two-stroke outboards
• Condition: new aftermarket replacement
• Contents: 12 pieces as pictured

Compatibility / Fitment Guide

Used on selected Mercury and Mariner 30–275 hp and Force 40–150 hp applications fitted with the matching square-style pump. Horsepower alone is not sufficient: compare the pump design and confirm one of the listed OEM numbers in the engine parts diagram.

Part Number Cross Reference

• Mercury/Quicksilver: 21-857005A1
• Mercury/Quicksilver: 857005A1
• Mercury/Quicksilver: 21-42990A7, A8, A9 or A10
• Sierra: 18-7817

Frequently Asked Questions

Is this a genuine Mercury or Sierra kit?
No. It is an aftermarket replacement cross-referenced to those numbers.

Is a complete fuel pump included?
No. This is a diaphragm and gasket repair kit for the existing pump.

How do I confirm fitment?
Match the pump shape and OEM number in the parts diagram for your exact engine serial number.