One of the most common problems is human error. For example, if fuel deliveries are normally 30,000 but then a delivery of 28,000 litres is received, it is likely this is entered (because of habit) as 30,000 Litres – three months later, there’s an unexplainable discrepancy. Looking back at the deliveries, everything looks fine, so it’s difficult to spot without going back through each fuel invoice.
Another problem is pump calibration. A pump will display and tell the fuel management system that it has dispensed, say, 200 litres when in fact, it has delivered 202. Over time, the tank ends up having less in than is calculated by the system leading to stock write-offs. It can work the other way, and the pump delivers 198 litres when it says 200, and you end up with more stock in the tank.
Short deliveries where you are billed for 30,000 litres but only get 28,000, and, finally, there is the possibility of the fuel being stolen from the tank. All of these issues are quickly detected if a tank gauge is fitted.