Gas coming out of exhaust pipe?

If you smell a lot of fuel out the tail pipe it usually means the injector or fuel line inside the intake manifold plenum is leaking. It also means that the converter and O2 sensors will probably need replacing due to the raw fuel. Sometimes you get lucky though.

Not a real hard fix but the parts are not cheap. If it's the pressure regulator or the lines the parts are about 50.00 If it is the injector itself you will need closer to 400.00

It's attached to the back side of the injector unit itself under the intake plenum. I usually just plan on replacing the entire unit and the fuel lines as well. About 350 bucks for a kit that includes all the parts.