1999 Chevy Malibu leaking fuel

Well have you notice any puddles of fuel under the vehicle? Is it from the front or the rear of the vehicle?

If it's at the rear check for rotted fuel lines first, most of the time they rot right above the fuel tank unforunately and you have to lower the fuel tank to probably repair the lines.

If it's from the front of the vehicle, check your fuel injectors, lines, fuel rail connections, etc.