System description

In order to prevent fuel vapors from entering the atmosphere, an EVAP canister is connected to the tank ventilation line.

Fuel vapors are collected in the EVAP canister. As the EVAP canister can only accommodate a certain amount of fuel vapors, these must be taken in and combusted during driving.

For this to occur, the EVAP canister purge valve (1) opens. Due to the vacuum predominating in the intake manifold, air is sucked up via the purge air line (3) through the EVAP canister. The air sucked up in this way draws the collected fuel vapors with it.

American law requires the tank ventilation system to be checked for leaks. For this purpose, the tank pressure sensor (5) and shutoff valve (6) are required.