Arrange the steps in the correct sequence to illustrate how fuel vapors move through an automotive Evaporative Emission Control (EVAP) system from initial generation to combustion.
- 1Liquid gasoline evaporates into vapor inside the fuel tank.
- 2Vapors flow through vent lines and are trapped in the charcoal canister.
- 3The engine computer commands the canister purge valve to open.
- 4Intake manifold vacuum pulls the stored vapors into the engine cylinders to be burned.
Answer
The correct sequence begins with gasoline evaporating in the fuel tank, followed by vapor storage in the charcoal canister, opening of the purge valve by the engine computer, and finally intake manifold vacuum drawing the vapors into the engine cylinders for combustion.
The Evaporative Emission Control (EVAP) system is designed to prevent unburned hydrocarbon vapors from escaping into the environment. The sequence begins when liquid gasoline warms up and evaporates inside the fuel tank. These vapors are routed through dedicated vent lines into a charcoal canister containing activated carbon that absorbs and stores them. When the engine reaches proper operating conditions, the powertrain control module opens the purge valve, allowing engine intake vacuum to draw the stored vapors out of the canister and into the combustion chambers where they are cleanly burned.
Step-by-Step Solution
Key Concept
Evaporative Emission Control (EVAP) system operation and fuel vapor pathway
Estimated Time:45s