Your gas tank explained in a single chart...

[Mopper]

If I'm seeing this right, inlet is near to filler-cap, up high on neck?

 

[Bad1975]

Two lines from the tank to the canister in the top back right corner and one from the canister to the neck.

The filler neck is slightly lower on the tank than the lines going to the canister. If you can see fuel in the neck you’ve put raw fuel into the canister more than likely.

IiRC the EVAP purge occurs 5 hours after last drive cycle, which you can hear an air pump in the box come on for 15-20 minutes during the purge cycle.

 

[Bad1975]

There is also what I believe is a roll over valve next to the can above the spare tire. Either way there is a fuel valve up there for something.

 

[Mopper]

There is also what I believe is a roll over valve next to the can above the spare tire. Either way there is a fuel valve up there for something.

It'd be surprising to me if all lines to the canister are open to one another. Any vehicle pitch the wrong way, accel/decels, etc, would throw fuel into the canister. But I don't know. Most importantly, I can't imagine that I DIDN'T introduce fuel to the canister. Outwardly, no ill effects so far. Not a practice I intend to continue, done purely for the sake of dimensioning the tank.

And I owe you two thanks as well @Bad1975 - 1) for teaching me what that pump sound was actually doing and 2) for teaching me that a gas flap opening has effects on following operations like battery start and DTE calculations. Thanks

 

[Bad1975]

There are electronic check valves inside the canister. One is going to be open during fueling to allow the tank to vent through the canister while fueling, the other line should prevent flow at all times into the canister and only allow return flow and there will likely be a third in the vent line to the filler neck so it can run EVAP pressure tests when commanded and not leak out the vented gas cap when pressurized.

Never dived into a newer setup, I wouldn't be surprised if the canister has a provision to return liquid back to the tank in the event of an overfill to limit damage to it.

What I can say is the days of syphoning fuel are gone. I bought a fuel pump to pump down my Tundra tank to replace the pump and sock but the hose wouldn't go down the filler neck. Checked with a fiber scope and there is plastic piece symbol looking triangle piece that blocks all but just a very very small hose from being able to enter and then takes a 90 turn into the tank so you can't drain a tank from the top anymore!

 

[MSINAL]

There are electronic check valves inside the canister. One is going to be open during fueling to allow the tank to vent through the canister while fueling, the other line should prevent flow at all times into the canister and only allow return flow and there will likely be a third in the vent line to the filler neck so it can run EVAP pressure tests when commanded and not leak out the vented gas cap when pressurized.

Never dived into a newer setup, I wouldn't be surprised if the canister has a provision to return liquid back to the tank in the event of an overfill to limit damage to it.

What I can say is the days of syphoning fuel are gone. I bought a fuel pump to pump down my Tundra tank to replace the pump and sock but the hose wouldn't go down the filler neck. Checked with a fiber scope and there is plastic piece symbol looking triangle piece that blocks all but just a very very small hose from being able to enter and then takes a 90 turn into the tank so you can't drain a tank from the top anymore!

This is why thieves have been drilling a hole in the tanks to get the fuel out since the anti-siphon valves came along. I'd rather people just be able to siphon it out, including me.

 

[Mopper]

I think the recommended way to drain the tank now is to pop the fuel line fitting (that is the current subject of a current recall?) open and pump the tank dry with the fuel pump?