Mine does this when it's hot outside. It seemed weird to me that it was when it was hot, so I tried (completely by chance) taking the gas cap off for a second and putting it back on. This works EVERY time. It's also making me think it has something to do with pressure in the tank. I thought it may be the cap, so I bought a new one, but same thing.

Maybe it is the fuel pressure regulator. I'll have to look into it.

Try removing the cap and putting it back on as an immediate fix though.

Cheers,
technocoy