Systems and methods for purging an exhaust reductant delivery system

A hydraulic system comprises a fluid tank and a pump, including a pump reservoir, fluidly coupled to the tank via a supply line. A valve is in fluidic communication with the pump reservoir via a pressure line. A backflow line fluidly couples the pump reservoir to the fluid tank via a timer reservoir and an orifice included in the timer reservoir. The hydraulic system transitions between a normal state and a purge state. In the normal state in which the pump is on, a first portion of the fluid is communicated from the pump reservoir to the valve and a second portion of the fluid is communicated from the pump reservoir to the tank. In the purge state, the pressure line and valve are purged followed by the backflow line and the pump reservoir such that no fluid remains in the pump reservoir.