If clamps seem to be OK and you had recently fueled up, sometimes if you really top it off you wont get full on vapor lock but as the vehicle sits and pressure is released a small amount of gas can leak from the breather. Which is right behind the seats making the smell strong while sitting in the car compared to it smelling stronger near the engine if the clamps are not functioning. I had to have the clamps replaced as last summer mine started spraying fuel while driving.
