Pressure and flow ripple generated by a fuel pump have essential impact on static and dynamic performances of an engine control system. It is especially dangerous for open-loop control used at a turbojet starting mode. The fuel consumption deviation at the engine starting caused by nonlinear averaging of fluctuations over throttling elements can reach up to 25% of a nominal value and provoke engine stopping. In the paper, the method for calculation of the hydro mechanical system characteristics in the presence of fluid born noise and its application for the turbojet start control system are developed. The harmonic analysis and the least mean square (LMS) method for the restrictor performance linearization is used. To avoid influence of fuel flow disturbances on the engine static performance it is proposed to increase system accuracy at the starting mode by placing the hydraulic RL-filter into the control unit. The effect of the device was surely verified by the engine test results.