Try another gas pump. There are two pumps for unleaded gas, and two for Diesel.
If neither one will work, the problem may be with the Gasboy card reader. Notify the police, who will try to dispatch a Shop person to get the pumps working again, and go to a Skinny's store or an L and L Convenience Store who are able to fill a City of Abilene vehicle in an emergency. The receipt needs to show the vehicle number, the license tag number, and your clear signature.