A system and method for calculating the flow rate of a dispensing point or flow capacity of a pump and fuel delivery system and determining if the dispensing point or fuel delivery system has a blockage and/or a performance problem if the calculated dispensing point flow rate is other than expected. The calculated dispensing flow rate is calculated by collecting fuel tank level data points for a dispensing point that fall within start and stop events of the dispensing event. The slope of a fitted line to the fuel tank level data points is used as the indication of the flow rate of the dispensing point. Different mathematical techniques may be used to improve the flow rate calculation to compensate for the minimum resolution of collecting fuel tank level data and the dead time included in the data of a dispensing transaction.