My family name is Fulopp, with dieresis on both "u" and "o". I come from Slovakia, which used to be upper Hungary in the time of the Hungarian-Austrian Empire. I now live in Brussels, Belgium.
I know a brother of my grandfather moved to Florida at the beginning of the 20th century, and another to Panama.
If your grandfather's given name was "Josef" then it may indicate Slovak or Czech origin, as the name would be spelt different in Hungarian or German (but that is not guaranteed).
It is possible that we come from the same family. There are many people named "Fulop" but far fewer of those named "Fulopp".
Can you tell me more about your grandfather, where he was coming from, anything you know? There'sa bit about my immediate family on my website here: http://www.vacilando.net/fulopp/http://www.vacilando.net/fulopp/