alright, i get how the testing phase of the EVAP system works, but i want to know 2 conditions thats arent really specified.

correct me as necessary:

1. lets say the car is off, where is it venting/how is it venting? i'm assuming that the vent valve is normally open, and that the fuel vapors are essentially "trapped" inside the charcoal canister, but the "pressure" is essentially allowed to bleed off so you dont end up with a pressurized tank while the car is sitting?

2. car is on, running/idling, no testing. is it still just venting to air through the charcoal canister preventing the "smell" of fuel? or does it go through a purge phase where it applies vacuum to the canister to purge the extra vapors (other than testing for leaks in the system)

the reason i'm asking is i'm ditching the ECU, and i'm thinking of simplifying the system. trying to keep it like an on/off or passive system, basically either just venting through the stock canister to keep fumes under control, or making it a single switch i can throw on once the car is running at idle.

this'll be on a sumped tank "return" tank/system.