Sierra Fuel Pump Kit 18-7811

The Sierra 18-7811 Fuel Pump Kit is a rebuild kit designed for Mercury and Mariner inline 6-cylinder 2-stroke outboards. This kit restores proper fuel delivery by replacing worn diaphragms and internal components in mechanical fuel pumps.

Fitment Overview

This Sierra kit replaces Mercury OEM part numbers 66599A1 and 89031A1, along with GLM 40350 and Mallory 9-37756. These part numbers identify a fuel pump family used on Mercury inline-6 engines.

Compatibility

These engines use a mechanical diaphragm-style fuel pump associated with the 66599A1 / 89031A1 fuel pump assembly.

Example Model Applications

• Mercury 90HP inline-6 2-stroke models
• Mercury 115HP inline-6 2-stroke models
• Mercury 140HP inline-6 2-stroke models
• Mariner equivalent inline-6 models

These are typical applications. Always verify by matching your OEM part number.

Fits These Serial Ranges

This fuel pump kit is used across multiple Mercury inline-6 engine generations and does not follow a single serial-number break.

Important: Confirm compatibility by matching your existing fuel pump or OEM number to 66599A1, 89031A1, 18-7811, 40350, or 9-37756.

Need the alternate fuel pump kit for a different pump style?
View Pro Marine Fuel Pump Kit 115 (A3 Style)

Part Numbers and Cross References

What This Part Is Used For

This kit rebuilds diaphragm-style fuel pumps by replacing worn internal components such as gaskets, valves, and diaphragms. It restores proper fuel flow and pressure to the engine.

• Rebuilds mechanical fuel pump assemblies
• Restores fuel pressure and delivery
• Helps eliminate fuel starvation issues
• Supports reliable engine performance

A failing fuel pump can cause hesitation, stalling, hard starting, or poor acceleration.

System Function and Connections

• System Type: Mechanical fuel delivery
• Pump Type: Diaphragm fuel pump
• Location: Engine-mounted fuel pump assembly

FAQ

What engines does this kit fit?
It fits Mercury and Mariner inline 6-cylinder 2-stroke outboards in the 90HP, 115HP, and 140HP range using the A1-style fuel pump.

What is the difference between this and the A3 kit?
This kit fits the A1-style fuel pump (66599A1 / 89031A1). Some engines use a different pump design that requires the A3 kit.

How do I confirm fitment?
Match your fuel pump number or OEM part number to the cross references listed above.

What are signs of a bad fuel pump?
Hard starting, fuel starvation, hesitation, or engine stalling.

Searchable Part Numbers

18-7811, 66599A1, 89031A1, 40350, 9-37756, Sierra fuel pump kit, Mercury inline 6 fuel pump kit, Mercury 115 fuel pump rebuild kit