How does the Evaporative Emission System (EVAP) work?

The Evaporative Emission System (EVAP) is designed to store and dispose of fuel vapors before they are released into the atmosphere. Not only does this help the environment, but it also helps fuel efficiency and keeps the gasoline smell out of your cabin. So basically, these systems are designed to store and dispose of fuel vapors.

There are several types of EVAP systems, but the standard system is comprised of your fuel tank, gas cap, liquid-vapor, fuel tank pressure sensor, separator, evap canister, and series of tubes and valves. These parts work together to purge the harmful hydrocarbons.

When the fuel evaporates inside your gas tank, the harmful vapors get moved to a charcoal canister stored at the front of your vehicle. When the fuel to air mixture becomes normal, it's transferred back to the engine. After this process, a valve makes a vacuum, drawing vapors into the engine. These vapors combine with fresh air from built-in vents and valves for more efficient combustion. This process is controlled mechanically or by computer, depending on the age and type of vehicle.

With so many moving parts in a sealed system, over time, EVAP systems are at risk of failure and leaks. These failures result in a check engine light popping up on your dashboard. Different leaks will provide different codes, with the most common being a loose gas cap. A hole the size of a needle can trigger a code, so leaks can be challenging to find. Technicians use scan tools, smoke machines, and other parts to find leaks. Not only leaks, but a blocked vent, bad purge flow, and other issues can pop up on a bad EVAP system.

A hole the size of a needle can trigger a code, so leaks can be difficult to find. At Ferber's Tire and Auto, our technicians use scan tools, smoke machines, and a visual to find leaks. Are you looking for a great EVAP diagnostic in Ashland? Call Ferber's for a diagnostic today!