Why do californians pay more for gas?
I deliver gasoline (not in California) but I think it is a combination of higher state taxes and stricter emission standards.
Another commone sence answer. it keeps clicking because it is telling you that your gas tank is full and if you don't stop trying to add more gas then it will overflow on the ground. I am sure you don't want to pay for gas on the ground but then again you probably want to know why you have to pay for the gas you just wasted since you didn't know why the pump clicks.