This is what I believe you are asking about ... not sure about the noise you are hearing

EVAP PURGE SOLENOID
DESCRIPTION
This vehicle uses a pulse-width modulated EVAP Purge Solenoid. The solenoid regulates the rate of vapor flow from the EVAP canister to the throttle body. The PCM controls the frequency at which the solenoid operates in order to customize the vapor volume for each cylinder.
OPERATION
The PCM will only energize the EVAP solenoid when the engine is at operating temperature, but will de-energize it during periods of deceleration. When de-energized, no vapors are purged. The pulse-width modulated EVAP Purge Solenoid controls the fuel vapor purge rate from the Vapor Canister and fuel tank to the engine intake manifold.