EVAP System Components

WARNING: This page is about a different variant/trim than selected.

The EVAP system consists of the following components:

EVAP Purge Solenoid Valve

The EVAP purge solenoid valve controls the flow of vapors from the EVAP system to the intake manifold. The purge solenoid valve opens when commanded ON by the ECM. This normally closed valve is pulse width modulated (PWM) by the ECM to precisely control the flow of fuel vapor to the engine. This valve will also be opened during some portions of the EVAP testing when the engine is running, allowing engine vacuum to enter the EVAP system.

EVAP Canister

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

Fuel Tank Pressure Sensor

The fuel tank pressure sensor measures the difference between the pressure or vacuum in the fuel tank and outside air pressure. The ECM provides 5 V reference, ground and signal circuit to the fuel tank pressure sensor. Depending on the vehicle, the sensor can be located in the vapor space on top of the fuel tank, in the vapor tube between the canister and the tank or on the EVAP canister. The fuel tank pressure sensor provides a signal voltage back to the ECM that can vary between 0.15 - 4.85 V. A high fuel tank pressure sensor voltage indicates a fuel tank pressure. A low fuel tank pressure sensor voltage indicates a fuel tank vacuum.

EVAP Leak Detection Pump Assembly

The leak detection pump assembly consists of three main components. These components are integral parts of the EVAP leak detection pump assembly and are not serviceable.

EVAP leak detection pump with reference orifice
EVAP leak detection pump switching valve
EVAP leak detection pump pressure sensor

This leak detection pump assembly is used for fuel tank pressure sensor correlation and leak checking the EVAP system for small and large system leaks.

EVAP leak detection pump pressure sensor's primary purpose is to perform leak detection diagnostics. The sensor itself is diagnosed by a correlation to barometric pressure based off the MAP sensor.
EVAP leak detection pump 0.51 mm (0.020 in) reference orifice, working in conjunction with the EVAP leak detection pump and pressure sensor. This orifice is used to establish a vacuum reference baseline for diagnosing EVAP leaks
EVAP leak detection pump switching valve switches from a vent position to a pump position depending on the EVAP diagnostics taking place.

Fresh Air Filter

An in-line 5 micron air filter exists between the EVAP leak detection pump fresh air intake and behind the fuel tank fill door pocket to keep the pump hardware from becoming contaminated.

Vapor Recirculation Tube

A vapor path between the fuel fill pipe and the fuel tank is necessary to fully diagnose the EVAP system. It also accommodates service diagnostic procedures by allowing the entire EVAP system to be diagnosed from the either end of the system.

Fuel Fill Cap, Capless if equipped

The fuel fill cap/capless fuel fill is equipped with a seal and has no relief valve.

Fuel Fill Pipe Check Valve

The check valve on the fuel fill pipe prevents spit-back during refueling.