Abstract: The disclosure illustrates an anti-tampering fuel control valve for a fuel system providing fuel at a regulated pressure to a series of unit injectors on a diesel engine. The injectors are cam actuated to inject fuel quantities related to the pressure of the fuel supplied to them. The control valve bypasses fuel from the output of the fuel system to a low pressure region when the pressure exceeds a first given level because of fuel system tampering. Orifices in the bypass flow path cause the fuel pressure to follow a schedule generally similar to the normal system pressure schedule but at lower levels. Bypass flow is continued until the fuel system pressure drops to a lower pressure than the pressure at which bypass flow begins.