Section 03-13: Evaporative Emissions
1993 Mustang Workshop Manual
DESCRIPTION AND OPERATION

Fuel Tank Vapor Orifice and Rollover Valve Assembly

Fuel vapor in the fuel tank is vented to the carbon 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 carbon canister. The vapor space also allows for thermal expansion of the fuel.