The evaporator (EVAP) canister on a Chevrolet Silverado is part of the fuel-evaporative-emissions-control system. The canister is filled with activated charcoal, and is designed to absorb fuel vapors from the fuel tank when the engine is running. The EVAP system then sends the vapors into the engine intake system, where they are mixed with the incoming fuel/air mixture to be burned during combustion. Over time, the charcoal in the canister can fall apart, and affect associated valves. It can also cause the Silverado's check engine light to come on.
Set the Silverado's emergency brake. chock the front wheels. Raise the rear of the vehicle with a jack, and place it on jack stands.
Locate the EVAP canister, attached to a bracket next to the fuel tank, on the driver's side of the truck.
Disconnect the quick-connect hoses from the EVAP canister -- squeeze the retainer tabs together and pull the large hose off the canister. Push the locking tab in, and pull off the smaller hose.
Remove the EVAP canister's bracket mounting bolt with a socket wrench. Remove the canister from the bracket.
Install the new EVAP canister to the bracket, and tighten the mounting bolt with a socket wrench. Replace the quick-connect hoses by pushing them into the fittings; the tabs will snap, when the hose is secure.
Lower the vehicle to the ground.
