Isuzu: Isuzu gas fumes, isuzu rodeo, gas fumes

I have a single lady friend that has a 1994 Isuzu Rodeo, while driving she get gas fumes into the inside passenger compartment. Also after driving and stopping, the fumes are near the rear area by the fill spout. I have looked at the auto and I see no visible signs of gas leaking. Would this be caused by a defective gas cap or other parts associated with the fuel tank.  The hose going to the fuel tank are not broken, as far as I can tell. Need some ideas on what to look for. Thanks.....Ronnie...............

Ok, I would suggest a couple cheap/free things first off. First inspect the threads around that the gas cap fit on. Next, buy a new gas cap. They are cheap and it could be the reason. I also suggest checking the net to see if Isuzu has made any recalls that fit this problem.

If nothing solves the problem, I would take this to a certified mechanic (preferrably one that does a lot of Isuzus) and have them look at it. This could become a serious safety issue.