Overview

The Attwood Marine 9300FDV7 is an in-line fuel demand valve for portable marine fuel systems that lets fuel move only when the engine is actually pulling it through the line. It installs between the fuel tank and the primer bulb, fits 5/16 in. and 3/8 in. fuel hose, and maintains flow up to 125 L/h with less than 2 kPa restriction.

On boats that use sealed portable tanks, pressure can build in the line before startup. This valve helps stop that fuel from being pushed toward the engine too early, which can cut down on flooding, fuel spillage, and the pressurized fuel slug that can hit the engine when the system is already under pressure. It also has a built-in manual override, works with ethanol-blended fuel, and is rated for operating temperatures from -4°F to 176°F with 20 psi nominal input pressure and protection for pressure spikes up to 40 psi.

Key features

• Fits 5/16 in. and 3/8 in. fuel hose for straightforward integration into common portable outboard fuel lines
• Installs inline between the fuel tank and primer bulb where pressure control matters most
• Allows fuel flow only on engine demand, helping reduce engine flooding and downstream fuel spray
• Low restriction of less than 2 kPa at 125 L/h helps maintain normal startup and running fuel flow
• Built-in manual override for added control when setting up or servicing the fuel line
• Composite body and ethanol-fuel compatibility suit routine marine fuel-system use
• EPA-certified and CARB-approved for pressurized portable fuel tank applications
• Compatible with OEM engine brands used across common outboard fuel-system setups

Installation and fit

This valve is a practical match for boats that run portable outboard tanks and need an inline valve to manage tank pressure before fuel reaches the engine. The main fit check is hose size and line layout: your system needs 5/16 in. or 3/8 in. hose and enough straight run between the tank connection and primer bulb for a clean installation.

For day boats, tenders, skiffs, and other small craft that spend time in the sun with fuel left in the line, this type of valve can help keep startup more predictable after the tank has built pressure at the dock or during transport. It also suits owners replacing a worn fuel-line valve and trying to keep fuel handling cleaner around the engine connection.