A pressure tank fault detector and method provides a system for detecting a fault in a pressure tank, such as a well water tank. The system includes a current transformer positioned adjacent a pump power wire. A circuit includes a timer, a data recorder, and a system status indicator. When the pump operates, the current transformer sends a signal to the circuit and the timer measures the signal duration. The data recorder logs a short cycle when the timer measures less than a selectable predetermined amount of time. When two or more short cycles are recorded, a signal indicates that a tank fault has been detected. Preferably, the system includes a test circuit and permits a user to select the number of short cycles before the alarm and whether to record only consecutive short cycles. Optionally, the system detects and signals pump cycles that exceed a predetermined excessive run time.