Why do I smell gas fumes in my focus

Hello, You may have an exhaust manifold gasket leak. The air that comes through the vents enters through the cowl, right under the windshield wipers. If the exhaust manifold gasket is leaking, you will suck the fumes right through the vents. Now, if the vents smell great, but you still smell the fumes, look under the rear seat to see if the fuel pump sealing ring is leaking.fuel. I would, however, expect a check engine light if it were.