A year after getting knocked out in their opening match, the three-time U.S. Open Cup champion Sounders advanced to the fifth round. Seattle will host fellow MLS squad San Jose next Tuesday night.
Evans' goal came after Aaron Kovar was taken down in the penalty box. Defender Zach Scott scored on a header in the 40th minute and Cooper made it 3-0 just before halftime.
Cooper scored in the 56th minute on a bicycle kick off a scramble around the goal and Federal Way's Sean Okoli capped the scoring with a tap-in goal in the 85th minute.
The match was Seattle's first since June 7. They don't return to league play until June 28th. That's because the MLS is taking a two week break for the World Cup.