Liquid Vapor Separator: Description and Operation

Fig. 47 Fuel tank vapor valve:

The vapor orifice rollover valve assembly vents fuel vapor to the charcoal "carbon" canister. The valve is mounted in a rubber grommet in a central location on top of the fuel tank.

Fuel Tank Fuel/Vapor Separator Operation:

As fuel vapors are generated, they enter the valve from the bottom, rise upward past the float, and out through a single vapor line to the carbon canister.
If liquid fuel should enter the valve assembly, the float will rise upward and close the orifice. As the fuel is drained back into the fuel tank, the spring attached to the underside of the valve pulls the float downward, exposing the orifice.

NOTE: In the event of vehicle roll-over, the float closes off the valve, preventing fuel from escaping and saturating the charcoal "carbon" canister.