The EVAP system consists of the following components

The EVAP canister is filled with carbon pellets that are used to absorb and store fuel vapors. Fuel vapor is stored in the canister until the PCM determines that the vapor can be consumed in the normal combustion process.

The EVAP canister has 2 ports.

1. Vapor pipe
2. Purge pipe

The EVAP purge valve controls the flow of vapors from the EVAP system to the intake manifold. This normally closed valve is pulse width modulated by the PCM to precisely control the flow of fuel vapor from the EVAP canister to the engine.

The fuel sender assembly is used by the EVAP system to collect fuel vapors at the top of the tank, and provides for the connection of the EVAP vapor pipe.

The EVAP vapor pipe provides a path for fuel vapors to move from the fuel sender to the EVAP canister.

The EVAP purge pipe provides a path for the fuel vapors to move from the EVAP canister to the EVAP purge valve.

The evaporative emission (EVAP) system limits fuel vapors from escaping into the atmosphere. Fuel tank vapors are allowed to move from the fuel tank (due to pressure in the tank), to the fuel sender assembly, through the vapor pipe, into the EVAP canister. Carbon in the canister absorbs and stores the fuel vapors. Excess pressure is vented from the EVAP canister to atmosphere. The EVAP canister stores the fuel vapors until the engine is able to use them. At an appropriate time, the PCM will command the EVAP purge valve open, allowing engine vacuum to be applied to the EVAP canister. Fresh air is drawn through the canister, pulling fuel vapors from the carbon. The air/fuel vapor mixture continues through the EVAP purge pipe and EVAP purge valve into the intake manifold to be consumed during normal combustion.