Attwood In-Line Fuel Demand Valve

The Attwood In-Line Fuel Demand Valve (Model 9300FDV7) is a critical fuel system component designed to prevent engine flooding and fuel spillage in marine and automotive applications. This valve solves a common problem faced by mechanics and enthusiasts: pressurized fuel reaching the engine when it shouldn't, causing hard starts, fuel odors, and potential overflow conditions. Whether you're troubleshooting a rebuilt fuel system or upgrading an aging engine installation, this demand valve ensures fuel delivery occurs only when the engine actually requires it during cranking and operation.

The valve operates on a demand principle: it remains closed until engine vacuum or fuel pressure signals demand fuel flow, then opens to supply the carburetor or injection system. This passive, mechanical design requires no electrical input, making it exceptionally reliable and maintenance-free throughout extended storage periods and seasonal use cycles. The inline configuration allows installation directly into the fuel line between the pump and engine, minimizing system complexity while maximizing fuel delivery control. At just 1 pound, the compact design integrates seamlessly into tight engine bays without requiring dedicated mounting hardware or brackets.

Mechanics and boat owners particularly benefit from this valve when rebuilding aging fuel systems, as it provides an inexpensive insurance policy against carburetor overflow and fuel leaks—common issues in vehicles exposed to heat cycling or prolonged idle periods. The valve is compatible with standard fuel line configurations and pairs well with mechanical fuel pumps, carbureted engines, and legacy fuel systems where fuel pressure regulation is critical. Installation takes minutes using standard hose clamps, making it an ideal retrofit for anyone seeking to improve fuel system reliability without complete system overhauls.