GM 17087069 Valve,Evap Emission Canister Control

This system is designed to trap and store fuel vapors that evaporate from the fuel tank, throttle body, and intake manifold. It consists of a charcoal-filled canister and the lines connecting the canister to the fuel tank, ported vacuum, and intake manifold vacuum. Fuel vapors are transferred from various components to the canister where they are stored when the engine is not operating. When the engine is running, the fuel vapors are purged from the canister by intake air flow and consumed in the normal combustion process. The ECM operates a solenoid valve to control vacuum to the purge valve in the canister. Under certain conditions, the solenoid is turned on to close the valve and block vacuum to the canister purge valve. The solenoid is turned off to allow purge when the engine is warm and meets specific criteria. The control valve prevents purge to the intake manifold under low vacuum conditions. If the solenoid is open or not receiving power, the canister can purge to the intake manifold at all times, causing rough idle or rich operation. Inoperative purge valve, damaged canister, split or cracked hoses, or incorrect hose connections can result in poor idle, stalling, and poor driveability. Evidence of fuel loss or odor can indicate issues such as fuel leaks, damaged canister, inoperative valves, or faulty hoses. Inspecting and repairing or replacing hoses, canister, and components as necessary is recommended. Component replacement instructions for the fuel vapor canister solenoid and canister are provided.