Systems and methods for purging an exhaust reductant delivery system

An exhaust reductant delivery system 100 comprises a pump 104 which receives reductant from a reductant tank 102 and is operable between a normal state and a purge state. A pump reservoir 106 can receive reductant from and provide reductant to the pump. A valve 108 of an injector or doser is separated from the pump by the pump reservoir and can receive reductant from and provide reductant to the pump reservoir. A timer reservoir 110 is separated from the pump by the pump reservoir and can receive reductant from and provide reductant to the pump reservoir. A backflow line 105 is provided between the timer reservoir and tank and can receive reductant from the timer reservoir and provide reductant to the timer reservoir. The pump provides reductant from the tank to the pump reservoir when operated in the normal state, and creates a first negative pressure at the pump outlet when in the purge state. A method of operating the system further includes creating a second negative pressure in the pump reservoir and a third negative pressure in the backflow line when the pump is in the purge state.