Boss, i thimk paki fx dont have such setup. you do following things:
change all rubber pipes to new, buy some best quality rubber pipes used for fuel and not the local ones.
take out the fuel tank and seal the fuel gauge with sealant so no fumes get out
there is a breather filter on fuel tank change it
change the plastic fuel filter beneath the car
check the pipe from where the fuel goes in and the area whether it is rusted or not
Moreover also check do u get the smell while driving the car with windows open or all the time whether open or closed.