Evaporative Emissions System: Description and Operation
Evaporative Emission ControlThe fuel tank is designed with a limited fill feature which allows about 10 % fuel expansion. The vapor pipe connected to the filler neck is connected into the tank at the maximum fuel level When the fuel covers the bottom of the vapor tube, fuel rises in the filler neck shutting off the fuel delivery nozzle. Purging and control of vapor flow to the canister are identical to the 1990 model year system.
Evaporative Emission Control:
Evaporative Flange
The top of the fuel tank incorporates a removable evaporative flange with three outlets. One outlet is used for the filler neck vent hose on 1991 model year vehicles and is capped-off on later vehicles. The center outlet incorporates a 2.5-3.0 psi pressure relief valve and is connected to a relief tube that vents to under the vehicle. The third outlet incorporates a rollover valve and connects to the charcoal canister. Electrical connection to the fuel pump module is made through the evaporative flange.
Evaporative Flange:
