Various “no filter, no run” fuel filtration designs are described that include a variable restriction orifice (VRO) designed to vary the amount of fluid, for example fuel, that reaches a fluid outlet. The VRO has a fully open position at which a maximum non-zero fluid flow is permitted, and a fully closed position at which a limited amount of fluid can flow to the outlet. In the case of diesel fuel, the amount of fuel flow permitted at the fully closed position provides lubrication of downstream fuel system components, for example the fuel pump, but is insufficient to permit engine operation.