Carp, who also homered in the third inning, has a 15-game hitting and 17 RBI in August, most in baseball for the month. It was his first two-homer game.
Wells homered in his third game in a row.
Eric Thames and Adam Lind had two-run home runs for the Blue Jays and Brett Lawrie had a solo shot.
Tom Wilhelmsen (1-0) earned his first major league win by working a 1-2-3 eighth inning.
Brandon League, a former Blue Jay, earned his 30th save in 34 opportunities for Seattle.
It was a rollicking first four innings, with nine runs and four lead changes.
The Jays got to Mariners starter Michael Pineda quickly. Yunel Escobar drew a game-opening walk and Thames connected on a first-pitch fastball, sending it deep into the seats in right field for his seventh homer.
The Mariners responded with three runs in the second off Henderson Alvarez, who was making his second major league start. Alvarez hit Wells in the back to open the inning. With one out, Trayvon Robinson drove a fly ball over the head of Thames in left for an RBI double.
Kyle Seager walked then Jack Wilson directed a single through a hole on the right side to score Robinson and send Seager to third. Ichiro Suzuki followed with a sacrifice fly that made it 3-2.
Pineda got in trouble again in the third, walking Jose Bautista followed by Lind’s two-run shot that cleared the wall in right, his 21st.
Carp tied it with his fifth home run with one out in the third. He has reached base safely in 24 consecutive games.
Lawrie then hit his third home run in his 10th game for the Jays, a leadoff shot in the fourth for a 5-4 lead.
Alvarez went five-plus innings, allowing four runs and six hits. He walked one and struck out three.
The Mariners are 20-21 in one-run games.
M’S SIGN HULTZEN
Danny Hultzen, taken by the Mariners with the No. 2 pick of the amateur draft, agreed Monday night to an $8.5 million, five-year contract.
The deal includes a $6.35 million signing bonus.
Hultzen, a 6-foot-3 left-hander, was 12-3 with a 1.37 ERA in 18 starts for Virginia. In three seasons, he was 32-5 with a 2.08 ERA.
Because Hultzen still had one more year of eligibility at Virginia, the Mariners had until 9 p.m. (PDT) to sign him.
MORROW’S RETURNS
Brandon Morrow will make the first start of his career at Safeco Field as a member of the Toronto Blue Jays on Wednesday, and he had fun Monday when asked about his memories of pitching for the Seattle Mariners.
“My memories here? I had a 3-2 count on every hitter I ever faced,” he said, laughing.
Morrow was traded in December 2009 for reliever League in a deal that seems to have worked out for both teams. After being the Mariners’ setup man last season, League has been their closer in 2011 and has recorded 30 saves.
And Morrow? A year ago in 26 starts, he went 10-7 for the Blue Jays and this season is 8-7 with a 4.55 earned-run average in 21 starts.
KENNEDY RESTS
Adam Kennedy has played only once in the first four games of the homestand, sidelined by an ailing heel injured last week in Texas.
“He’d go out there in a second if I put him in a game,” manager Eric Wedge said, “but we owe to him to give him the time to let it get better.”
SHORT HOPS
Franklin Gutierrez lined a first-inning double to extend his hitting streak to eight games. … In his first 23 games after being recalled from Tacoma, Carp had 24 RBI – the fifth highest total in the majors since that date. The leader? Arizona’s Justin Upton with 29.
ON TAP
Seattle hosts Toronto in a 7:10 p.m. game today that will be televised on Root Sports. Probable starting pitchers are Brad Mills (1-2, 6.46 ERA) vs. Jason Vargas (7-10, 4.01).
Staff writer Larry LaRue contributed to this report.
TODAY
Toronto (Brad Mills: 1-2, 6.46 ERA) at Seattle (Jason Vargas: 7-10, 4.01), 7:10 p.m., Root Sports, 1240-AM, 1030-AM

