Fuel Tank Pressure Release Valve: Description and Operation

Two-Way Valve:

PURPOSE
The Two Way Valve, located on top of the fuel tank, vents fuel tank vapor pressure into the charcoal canister.

OPERATION
When fuel tank pressure exceeds 10 to 35 mmHg (0.4 to 1.4 in.Hg.) the Two-way Valve opens. Once open, the fuel tank vapors are bled off into the charcoal canister until pressure drops below 10 to 35 mmHg (0.4 to 1.4 in. Hg.) The Programmed Fuel Injection Electronic Control Module (PGM-FI ECM) then determines when to draw the vapors from the canister into a port on the throttle body.