A system for warning that a fuel line nozzle should be removed from a gas tank, by: determining that a fuel pump nozzle has been tilted from its resting position in a pump cradle to a refueling position where it has been inserted into a gas tank tube; and then determining that fueling through the fuel line has stopped by detecting vibration of the fuel pump nozzle when the fuel line shuts off; and then activating an alert system including a warning light and an audible sound if the fuel pump nozzle has not been removed from the gas tank tube and returned to the pump cradle after a predetermined period of time. The system can also wirelessly transmit fuel line use data to a remote computer.