Evaporative Check Valve: Description and Operation

Overfill Limiter (Two Way Valve):

Location
Mounted in-line on the vapor line at the forward end of the fuel tank.

Construction
The overfill limiter consists of a pressure valve and a vacuum valve.

Operation
The pressure valve is designed to open when the fuel tank internal pressure has increased over normal pressure and the vacuum valve opens when a vacuum has been produced in the tank.