I am having trouble filling my gas tank on a 1995 mazda 626. When I pull the lever on the hose while filling my tank it always shuts off like my tank is full almost immediatly. You can hardly get any gas in it. The last time I had it in I told my mechanic and he said everything looks fine from the outside. He said he could start taking it apart but it would probably cost a few hundred dollars. Does anybody have any clues.