Evaporative Emission Pressure Control Valve

Tank Pressure Control Valve:

DESCRIPTION
When gasoline vapor in the fuel tank builds enough to overcome the spring tension of the Evaporative Emissions (EVAP) Pressure Control Valve, the vapor will flow to the canister where it is absorbed and stored by the charcoal.

OPERATION
When vapor pressure in the fuel tank exceeds approximately 5 kPa (0.7 psi) the tank pressure control valve diaphragm opens, allowing vapors to vent to the canister. A 1.14 mm (0.045 in.) orifice in the passage leading to the canister tube causes pressure to drop slowly, preventing the valve from oscillating (buzzing). When the tank pressure drops below 5 kPa (0.7 psi) the diaphragm valve closes, causing vapors to be held in the fuel tank.