Smelling gas inside car. No visible leaks on 1999 Pontiac Montana

The fuel tank pressurizes and gas smell is strong inside car.More in hot weather. Fuel tank blows back hard when the cap is removed.

Asked by for the 1999 Pontiac Montana
The most likely cause of your concern is a malfunctioning evaporative emission system. This system contains the raw fuel vapors and burns them in your engine when the computer opens a valve electronically. A clogged carcoal canister may be the culprit, but a professional that understands the system needs to give it a look.
Thanks, I changed the canister some time back but that didn't help.