Abstract: The function of premodule crude oil back pressure regulating valve is to satisfy the requirements of flow rate and pressure of crude oil for fuel selecting module by adjusting the bypass oil flow from crude frontmounted pump outlet. Because the control pipe is so petty that blockage is easy to occur,there were some other faults, such as membrane aged and broken, pressure unsteady, etc. in the system. So the reformation was carried out in 2007, the regulating valves was backout, frequency conversion control was used for fuel flow rate adjusting. Two altering way reformation scheme were introduced and their advantages and disadvantages were analyzed, and the existing problems were pointed out in this paper.

Key words: back pressure regulating valve, frequency conversion control, advantages and disadvantages