My garage is beginning to smell like gas because my 240z is emitting gas fumes while it's parked. What are the most common causes for gas fumes? I ordered a new fuel filler hose and I was wondering if there are any other fuel hoses that commonly crack on these cars.

You bet, there are a few ''vapor'' recovery hoses that can cause this. For starters look by the muffler at the lower rear of the fuel tank. This hose runs up into the cabin area to a evap tank that hides in back of a plastic panel where the filler is located. This is a likely a source for your problem. If you do a search on removal of this tank you will find complete instructions . I removed this system years back and am happy I did so. I showed a member what to do and he posted the step by step. You might check the gage sender and the fuel supply and return lines while you are at it . They are together on the driver side of the gas tank.

Gary

Lots of info on this if you search for it. Multiple hoses and seals.