DeVille V8-4.9L VIN B (1995)
Evaporative Emission Control Canister: Description and Operation
Canister
DESCRIPTION
The 1.5 liter cylindrical inverted function canister is filled with activated carbon that stores vapor transferred from the fuel tank. A single tube
extends down the center of the canister to a liquid trap at the canister base. Fuel vapor/condensed liquid from the tank enters a port on the canister
cover. The vapor/liquid travels down a center tube where the vapor is absorbed by the charcoal and the liquid is stored in the lower well. Both are
contained until purged through the normal combustion process. The three ports coming off the canister are identified as:
a. Fuel vapor Port (from fuel tank)
b. Evaporative Emissions (EVAP) Port (purge line to throttle body)
c. Atmospheric Port (from fresh air source via the body mounted vent hose).
The EVAP solenoid which is integrally mounted, is controlled by the Powertrain Control Module (PCM) to regulate vapor flow from the
canister to the throttle body. The solenoid is normally closed and when certain engine parameters are met, the solenoid opens allowing engine
vacuum to purge the canister.
