Mechanic checked fuel system for leaks and codes and could not find a problem. Never the less, I cannot fill the gas tank properly as the pump keeps shutting off. Mechanic had no good ideas to diagnose this problem other than substituting several parts like the gas tank, evaporator box, valves, etc. and hoping it would fix things. He was reluctant to be more aggressive like forcing air into the gas lines for fear of causing an explosion.

He also was reluctant to disconnect parts of the system to observe the behavior as he said it was a government violation with stiff penalties for doing this.