2005 Ford Focus Refueling problem

I have the same issue with a Ford Focus ZX4 ST. I just rolled 50k and with whatever amount of gas in the tank, the pump shuts off after only about 1-10 seconds of pumping gas. It sounds as if the gas is having difficulty flowing into the tank due to a restriction somewhere. Most gas pumps shut off when gas reaches the nozzle during pumping. Changing the position of the pump handle has no effect, but it appears changing the rate of gas being pumped does. While exerting minimal pressure on the pump handle, a lower volume of gas is pumped over time which seems to alleviate the problem temporarily. Maintaining a low, fixed pressure is very difficult though.