removing Dirt Dobbers from vent

I am not sure what you mean by 'dirt dobbers'? If your fuel tank will not let in fuel, typically there is a jammed vent valve in the filler neck. This valve allows the air to leave the system as it is displaced by the entering fuel. There is also a canister vent valve that can get jammed up with carbon pellets from the canister that can get plugged up as well. Do you have a Check Engine Light on? Let me know. Good Luck!