Gas fill vent

You can find a couple diagrams on the Gen 3 stump-the-chump thread.

This one is schematic, to give an idea what components are present and how they are connected. It is only approximate as to where they physically are:



Notice it shows the "air filter" right up against an air inlet port located right with the filler neck.

That is where the port is, but it's not really where the filter is. The filter is the thing with the blue ? here. Callout *4 is the "air inlet port":



Notice there's quite a bit of stuff involved. The vapor you displace from the tank as you fill passes through the fuel fill check valve and fuel cut-off valve, follows the tank vent line into the charcoal canister, exits from there through the vent valve and the air "inlet" line (not so much an "inlet" while you're fueling), and out through the filter and the air "inlet" port.

Obstructions anywhere in that path could explain the symptoms.

Does this car have any history of fill-ups being "topped off"?

 

Does this system have the flow capacity to handle the air displaced during a fill? Or just the evaporation later?

P.S. How are you managing to post images this week? With the ongoing server migration issues, I'm not currently successful with attempts to include pictures.

 

I haven't tried uploading any images, only placing [img] links to images already existing.

That seems to be working ok for images hosted elsewhere than PriusChat, and also for images on PriusChat if I enter a direct URL (not one involving proxy.php). The URL in the resulting post ends up involving proxy.php, and the original image has been newly cached so it works.

I reported a problem where existing posts with proxy.php links to images that had been cached before the migration were busted. Don't know if that's fixed yet.

I think the EVAP/ORVR (onboard refueling vapor recovery) system does indeed handle the air going out during refueling. That has to pass through the charcoal canister, to make sure you're venting out just the air and not the HC vapors.

This diagram is for Gen 2 (warning Will Robinson, this diagram is for Gen 2)—you can tell by the bladder in the tank—but it gives a bit more explanation of the system.



In Gen 2, only what escapes from inside the bladder has to go through the canister; that then proceeds into the space around the bladder and out the Canister Closed Valve and Fresh Air Valve. In Gen 3 without the bladder, all the air leaving the tank is vapor-laden, so all the more important that it go through the canister on its way out.

 

Cut and paste function still works for images...