This is a fuel tank vapor valve for your 1979-93 Mustang. Your fuel tank is vented to the charcoal canister through the vapor valve assembly. The valve is mounted in a rubber grommet at a central location in the upper surface of the fuel tank. A vapor space between the fuel level and the tank upper surface is combined with a small orifice and float shut-off valve in the vapor valve assembly to prevent liquid fuel from passing to the charcoal canister. The vapor space also allows for thermal expansion of the fuel.
Year Range: 79,80,81,82,83,84,85,86,87,88,89,90,91,92,93