GMC 12630282 Valve Assembly, Evap Emission Canister Purge Solenoid

The EVAP system is used to lessen the chances of fuel system vapors, which contains unburn hydrocarbons, being released to the atmosphere. During hot weather, fumes in the fuel tank evaporate and, when the pressure is increased to a specific level, the fuel vapor vent valve and the fuel vapor control valve open to pump the vapors to the EVAP canister where they are temporarily stored until they can be burnt by the engine. The canister purge solenoid is opened by PCM under certain circumstances and the vapors produced are admitted into the intake manifold to be burnt with the air/fuel mix. The EVAP canister is a chamber which is mounted under the car but is full of activated charcoal and does not require any service. Fuel tank pressure sensor checks tank pressure and transmits with PCM during leakage tests. The vent solenoid is ON but isolates the system for the testing The canister purge solenoid is closed or opened by PCM depending on the signals from the intake manifold vacuum, sensor data that decides vapor flow. Some of the signs of EVAP system malfunction include fuel smell, poor start or idle, stalling, difficulty in accelerating and driving, and these are often as a result of defective vapor hoses and or fuel tank. To test for elements such as high fuel vapor pressure, the valve can be opened by taking off the gas cap in order to listen for pressure relief hissing. The other element of air intake service process is rather simple and consists in the removal of air intake duct, detachment of electrical connectors and quick-connect fittings, and the reconnection and installation of the air intake duct in the reverse order. The EVAP canister and the fuel tank pressure sensor, need the car to be lifted and supported on jack stands for removal and installation.

To remove the fuel tank pressure sensor, take out the fuel tank, disconnect the connector, and remove the sensor from the fuel pump module. To remove the EVAP canister, raise the vehicle, remove the fuel tank, disconnect the connector and hoses from the canister on top of the tank, and remove the retainer and the canister. Installation is the reverse of removal.

When conditions are right, the Powertrain Control Module (PCM) opens the canister purge solenoid, allowing vapors to be drawn into the intake manifold and consumed by the engine.