Sierra 18-7776-1 3/8 Inch Fuel Water Separator Filter Kit, Stainless Steel, 21 Micron

The Sierra 18-7776-1 is a 3/8 inch (9.5mm) fuel water separator filter kit built with a stainless steel outer housing for durability in a marine engine compartment. It is designed to protect inboard, sterndrive, and outboard fuel injection systems from the damage that emulsified water and contaminants can cause to injectors, carburetors, and fuel pumps. The filter carries a 21 micron rating and removes over 99.8% of emulsified water from gasoline before it reaches the engine, helping prevent hesitation, stalling, and long-term fuel system wear caused by ethanol-blended fuel absorbing moisture.

Rated to flow at 90 GPH, the 18-7776-1 is built to keep pace with higher-demand fuel systems rather than restricting flow under load. The stainless steel construction resists corrosion in the humid, saltwater-exposed environment typical of boat engine bays, making it a durable choice for a component that is replaced as routine maintenance. It installs on 3/8 inch fuel lines and functions as a genuine Sierra part offered as a direct OEM equivalent, so no separate cross-reference lookup is needed to specify the correct filter for a 3/8 inch fuel system.

Specifications

• Brand: Sierra
• Manufacturer Part Number: 18-7776-1
• Material: Stainless Steel
• Fuel Line Size: 3/8 inch (9.5 millimeters)
• Micron Rating: 21 Micron
• Flow Rate: 90 GPH
• Water Removal: Removes over 99.8% of emulsified water from gasoline
• Vehicle Service Type: Watercraft
• Unit Count: 1
• Weight: 2.16 pounds

Frequently Asked Questions

What size fuel line does the Sierra 18-7776-1 fit? The 18-7776-1 is sized for 3/8 inch (9.5mm) fuel line connections.

What is the micron rating of this filter? This Sierra fuel water separator kit carries a 21 micron filtration rating.

How much water can this filter remove from gasoline? It removes over 99.8% of emulsified water from gasoline before it can reach the engine's fuel system.

What is the maximum flow rate of the 18-7776-1? It is rated to flow at 90 GPH, enough to feed higher-demand fuel injection systems without restricting supply.

What material is the 18-7776-1 housing made from? The housing is stainless steel, chosen for corrosion resistance in a marine engine compartment.

Is the Sierra 18-7776-1 compatible with fuel injected engines? Yes, it is built to protect inboard, sterndrive, and outboard fuel injection systems from water and debris contamination.

Is the 18-7776-1 a genuine Sierra part or an aftermarket copy? It is a genuine Sierra-manufactured fuel water separator kit, offered as a direct OEM equivalent part.

How much does the 18-7776-1 fuel water separator kit weigh? The kit weighs 2.16 pounds.

How many filters come in the 18-7776-1 kit? The 18-7776-1 is sold as a 1-count fuel water separator kit.

Will the 18-7776-1 fit outboard, sterndrive, and inboard engines? Yes, the 3/8 inch Sierra 18-7776-1 is designed to work across inboard, sterndrive, and outboard fuel systems using a 3/8 inch fuel line.

How do I know if I need the 3/8 inch size instead of another size? Check the diameter of the existing fuel line at the filter connection; the 18-7776-1 is built specifically for 3/8 inch (9.5mm) line, so a different diameter line would require a different size filter.

Does this filter help with ethanol-related fuel problems? Yes, by removing over 99.8% of emulsified water from gasoline, the 18-7776-1 helps reduce the moisture-related fuel issues common with ethanol-blended gasoline.