Analysis of technical condition of diesels with accumulator Common Rail power supply system shows that the largest share of fuel equipment failures is associated with malfunction of high-pressure fuel injectors. The electronic engine control unit generates commands for biphasic fuel injection from each injector. Due to the wear of the injector elements, there is an uneven fuel supply to the engine cylinders and, as a rule, deterioration of its operation. (Research purpose) The research purpose is in studying the process of adjusting the fuel supply in the Common Rail system when diagnosing the engine of a Ford Transit vehicle. (Materials and methods) The most relevant method of commissioning Common Rail fuel system injectors are various service procedures, such as the Low Injection Training procedure. Authors used a scanner and appropriate software to estimate total fuel delivery at idle mode. Authors performed the study on a 2.4 liter Duratorq diesel engine. (Results and discussion) The article presents the engine parameters before and after adjustment (Small Injection Procedure). Before adjustment, two cylinders of the engine received more fuel than the other cylinders. It manifests in an increase in crankshaft speed. After the adjustment, the fuel supply to the cylinders was equalized, resulting in an equalization of crankshaft RPM, reduced vibration and noise. (Conclusions) The study showed that fuel adjustment and Low Injection Training should be a must for engine diagnostics. Correction is effective if the value of injection discrepancy is no more than 5 mg/stroke.