Well this is going to be an interesting one to debug, but you should be able to figure it out.
The first thing I would do is ensure you have and know which one is your wan port and which one is your lan port. This is on the pfsense os part. I have see where someone had the ports crossed em0 vs em1 and their router just didn't work. If you are absolutely sure you know your wan port from your lan port (no offense intended) then move on to the next step.
For testing ensure that you have a default firewall rule that allow basically src: any, dst: any, prot: any from your lan port to the internet. You can work on the filter rules in a bit. Once you have the any, any, any rule in place open a console session on the pfsense box. On the pfsense box ping 8.8.8.8 and see if you get a response. If not then do a traceroute to 8.8.8.8 and see where...