The stability of the values of cyclic feeds and the angle of the actual beginning of the fuel supply largely depends on the presence of the injection valve of the fuel pump section and its design features. The valve must reliably separate the discharge line from the pre-plunger space and, within certain limits, ensure the residual pressure in the discharge line between cycles. However, the installation of the valve causes a repeated reflection from the valve of the pressure impulses, that follow from the nozzle and leads to the appearance of additional injections or a sluggish fit of the needle on the sprayer seat. In order to eliminate negative consequences, double-acting injection valves are installed on distribution-type pumps, in which the pressure impulses are extinguished by transferring fuel through an additional non-return valve. The use of double-acting valves with non-return valves on distribution-type pumps ensures reliable unloading of the discharge pipe from the cut-off cavity. One of the main purposes of a non-return valve is to provide the necessary hydraulic density of the coupling pressure valve - non-return valve. Serial pumps are equipped with cross-shaped and round-shaped check valves in cross-section, which are designed to provide the same hydraulic tightness of the coupling pressure valve - non-return valve. In the course of research, the results of which are presented in the work, it was revealed that they have different sealing characteristics. In parallel, the characteristics of a triangular and square check valve in cross section were investigated. As a result of research, it was found that square valves have the best sealing characteristics. In the course of the research, it was also revealed that serial check valves of cruciform and round shapes do not provide their functional interchangeability, since they have different abilities to ensure hydraulic tightness of the interface with the discharge valve - non-return valve. Square-shaped check valves in cross-section are more technological to manufacture.