Failed smog test fuel tank not holding vacum

Okay so the canister is good all new hose. They clamp off the vent tub before the metal line running back to the tank. Then they test your cap at the machine. Then they crew a cap on you filler neck and apply vacuum. It failed the filler neck test. On the way back home I noticed gas smell inside the car. Also in the drive way outside you can smell it now. So once the grommet for the filler neck and my new stainless sending unit are installed should be good now. So I conclude that the vacuum finished off sending unit gasket or tank doughnut. Before the test i had no gas smell at all.