Raw fuel smell - not the garden variety TSB kind?

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I've been searching around this morning trying to figure out what's wrong with my 99 impreza and its fuel smell issues. I've seen much about the TSB and related loose fuel line info. I don't think that's what I have so I thought I would post and see if anyone can help out.

Symptoms: Car smells like gas inside after filling up. It will linger a little, but goes away if you air it out well. It doesn't do it every time we fill up maybe 1 out of 3 or so? It seems to be related to topping off the tank in that if you don't top off it doesn't smell as often.

Any thoughts? I'm wondering if maybe my charcoal canister has a clogged line or something?

Also, I've tried convincing my wife that she shouldn't be topping off anyway, but you know how that goes.