Carp finished with two home runs and extended his major league-leading hit streak to 15 games. Wells has homered in three straight games.
Trayvon Robinson went 3-for-4 with two doubles, an RBI and a run scored for the Mariners, who won their third straight.
Tom Wilhelmsen (1-0) worked a scoreless eighth to earn his first major league victory.
Jon Rauch (5-4) suffered the loss after surrendering Wells' home run.
Eric Thames and Adam Lind both had two-run homers for the Blue Jays.