trouble pumping gas

My girlfriend has a 2002 XG350. Recently we tried pumping gas went to a few different stations. Whenever we pump gas into the car it takes a gallon or so then clicks off as if we have a full tank and it won't take anymore. I though this might be the case and that the sending unit for the gauge was acting up. To my surprise this is not the case as we encountered quite an ordeal the other night when we ran out of gas in the middle of the road.

I'm guessing that there is something in the main fill line in or in the tank itself that is causing blockage.

Is there anyone that could lend a hand in trouble shooting this problem?

Thanks