A computer-implemented fuel dispensing system to facilitate use of a mobile device to purchase and dispense fuel from a dispensing site having an electronic point-of-sale system that mediates operation of at least one fuel dispensing pump using funds administered by a financial processing computer network, comprising: a site connector computer programmed to administer a site database and to provide a site connector interface adapted to be coupled securely to the point-of-sale system of at least one site; the site connector computer being programmed to define in said site database a data structure that stores site-specific information about the dispensing site including the site location and pump identifying information from which the number of pumps at the dispensing site may be ascertained; the site connector computer being programmed to communicate with the electronic point-of-sale system and populate a record in said site database according to said data structure using information obtained from said at least one site; a mobile app server computer programmed to support Internet communication with the mobile device and also to communicate securely with the financial processing computer network; the mobile app server computer being further programmed to communicate queries to and receive information from the site database; the mobile app server computer being further programmed to ascertain a site location from the mobile device upon user interaction via the mobile device and to use said site location to issue a query to the site database to acquire the pump identifying information from the site database; the mobile app server computer being further programmed to communicate the pump identifying information to the mobile device for use in making a pump selection based on the pump identifying information; the mobile app server computer being further programmed to receive from the mobile device a pump selection identifier and to issue a fuel purchase instruction that includes the pump selection identifier to the financial processing computer network wherein the site connector computer communicates with the point-of-sale system of at least one site independent of the mobile app server and the mobile app server receiving information from the site database. a site connector computer programmed to administer a site database and to provide a site connector interface adapted to be coupled securely to the point-of-sale system of at least one site; the site connector computer being programmed to define in said site database a data structure that stores site-specific information about the dispensing site including the site location and pump identifying information from which the number of pumps at the dispensing site may be ascertained; the site connector computer being programmed to communicate with the electronic point-of-sale system and populate a record in said site database according to said data structure using information obtained from said at least one site; a mobile app server computer programmed to support Internet communication with the mobile device and also to communicate securely with the financial processing computer network; the mobile app server computer being further programmed to communicate queries to and receive information from the site database; the mobile app server computer being further programmed to ascertain a site location from the mobile device upon user interaction via the mobile device and to use said site location to issue a query to the site database to acquire the pump identifying information from the site database; the mobile app server computer being further programmed to communicate the pump identifying information to the mobile device for use in making a pump selection based on the pump identifying information; the mobile app server computer being further programmed to receive from the mobile device a pump selection identifier and to issue a fuel purchase instruction that includes the pump selection identifier to the financial processing computer network wherein the site connector computer communicates with the point-of-sale system of at least one site independent of the mobile app server and the mobile app server receiving information from the site database.