[HMeeder]

Had much the same problem.

On my car, I did replace both the gasket under the fuel filler tube and the gasket in the cap. I would still ocassionally smell fuel, especially with a full tank. I discovered that my cap wouldn't always sit square with filler neck, resulting in a small gap. I used a pliers to bend the tabs on the cap to ensure a snugger fit. Still would smell gas every now and then. Then I discovered that after putting the cap back on if I pushed down on the cap I could sometimes get it to 'snap' lightly and snug up properly. Now I just press down on the cap every time fill and I haven't had the gas smell recur.

I would check in this order, gasket condition, cap fitment, canister hoses, fuel filler tube gasket, and finally, the fuel lines.