There's a charcoal canister tucked up under the front of the left front fender, only visible by peering up from underneath, under the valence by the left lower corner of the radiator/air intake scoop. Don't know if this is your problem, or one of the lines to/from it, which I think are for vapours from the tank.

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1986 560SL
2002 Toyota Camry
1993 Lexus