The paper presents a simplified methodology for generating the characteristic curve of fuel doses for common rail injectors, which consists in limiting the number of measurements on the test bench and calculating missing data using predefined (array) functions of the Microsoft Excel spreadsheet. This allows checking the method of fuel delivery in a wide spectrum of predefined pressures and atomiser opening times, while reducing the arduousness and time-consumption of the active experiment phase. The proposed solution is particularly useful in problematic situations when standard manufacturer's tests, referred only to selected work points, make it impossible to clearly assess the technical condition of the injector.