An electrochemical fuel cell stack with integrated anode exhaust valves is disclosed, comprising a plurality of fuel cells, each fuel cell having an anode and at least one anode flow field channel, an anode exhaust manifold fluidly connected to the at least one anode flow field channel of each fuel cell, and a means for minimizing fluid backflow from the anode exhaust manifold into the anode flow field channels of the fuel cells. Methods for purging, and reducing fuel cell voltage variations within, the electrochemical fuel cell stack are also disclosed.