evaporator status monitor won't set (no code)

thanks pcitizen & all for the related solutions to my p171-p174.i did the job in about 5 hrs. including a lunch break and all went well & the codes didn't come back on. even after all the repairs by various shops, ford, and even several gold test stations the fix was never resolved. The info on this web site is awesome. thanks again!
I have another problem this time with the evap . my OBD11 shows that the evap is not set and is always last and will not set. i'am having a hard time trying to set it. my question is if there is a problem in the evap system such as a vacuum leak etc why don't the PCM tell me a code related to that because as thinking having no codes & the fact the cel is off the vehicle would not have passed the smog test.I will search for leaks or breaks and follow through all related lines charcoal filter etc.I do smell gas in the rear area as of now have no definite find i can only assume maybe a leak or problem on the gas tank itself. ANY answers to this ?. i'm not sure if it's fumes or actual gas smell. yes i also changed the gas cap.