Component Description
- EVAP canister (1):
The canister is filled with carbon pellets used to absorb and store fuel vapors. Fuel vapor is stored in the canister until the control module determines that the vapor can be consumed in the normal combustion process.
- EVAP canister purge Valve (2):
The EVAP canister 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 control module to precisely control the flow of fuel vapor to the engine. The valve will also be opened during some portions of the EVAP testing, allowing engine vacuum to enter the EVAP system.
- EVAP canister vent solenoid valve (3):
The EVAP canister vent solenoid valve controls fresh airflow into the EVAP canister. The valve is normally open. The ECM will command the valve closed during some EVAP tests, allowing the system to be tested for leaks.
- Fuel tank pressure sensor (7):
The fuel tank pressure sensor measures the difference between the pressure or vacuum in the fuel tank and outside air pressure. The ECM provides a 5-volt reference and a ground to the fuel tank pressure sensor. The fuel tank pressure sensor provides a signal voltage back to the control module that can vary between 0.1 - 4.9 volts. As fuel tank pressure increases, the output voltage of fuel tank pressure sensor decreases, high pressure = low voltage. As fuel tank pressure decreases, the output voltage of fuel tank pressure sensor increases, low pressure or vacuum = high voltage.