The Stars have won their last three games, scoring 15 goals in the process.
Dallas had not had more than one power-play goal in any game this season, but produced four of them against the Coyotes. The Stars chased goaltender Ilya Bryzgalov, who made his 200th appearance for Phoenix.
Eriksson scored the only first-period goal but Richards had two goals in the first 5:21 of the second to send Bryzgalov to the bench. Bryzgalov allowed three goals on 18 shots.
Eriksson's second goal of the game and ninth of the season came with 2:51 left in the second period, giving the Stars a 5-1 lead.
Brenden Morrow added his 200th career goal in the third period and Kari Lehtonen stopped 25-of-28 shots.