The study proposes a technique, which allows to decrease the operating costs of motor transport enterprises on conducting maintenance services of motor and tractor equipment. Distribution of malfunctions with respect to the elements of fuel injection equipment of diesel engines is presented. The existing methods of troubleshooting diesel fuel injection equipment of double feed type with high pressure multicylinder fuel injection pumps are insufficiently informative or labour-intensive. The analysis of such fuel injection systems has shown that the displacement of the needle valve and the pressure in the high pressure line are the parameters that reflect the system operation to the fullest degree. A mobile diesel fuel injection system troubleshooting device was developed in the process of the investigation, which allowed to control such parameters as decreasing spring stiffness of plunger pair injection valve, plunger pair wear, injection angle distortion, non-uniformity of fuel feed to the cylinders. An evaluation of accuracy and effectiveness of troubleshooting by needle valve displacement parameter has been carried out for the developed method and the fuel injection equipment element control device. © 2018 Association for Computing Machinery.