Vladimir Guerrero had a two-run shot for Texas, which has lost five straight and nine of 12. Still, the Rangers began the day with a seven-game lead in the AL West over Oakland.
The Blue Jays lead the majors with 215 home runs this season, including a major league-high 119 at home. Toronto has gone deep in nine straight games, hitting 20 homers during that span. They've hit three or more home runs in a game 33 times, the most in baseball.
Wells hit two solo homers to left, one in the fourth inning and another in the seventh, giving him 27 on the season. The first was a towering shot into the fourth deck, the second was a liner into the corner. It was his third multihomer game of the season and the 21st of his career.
Buck hit a solo shot to right in the second, his 17th, and Lind hit a two-run drive off the center-field restaurant in the seventh, his 20th.
The crowd of 10,518 was Toronto's second-smallest of the season. The Blue Jays drew 10,314 on April 19 against Kansas City.
Shaun Marcum (12-7) allowed three runs and six hits in seven innings to win for the first time since Aug. 16 at Oakland and match his career high for wins. Marcum, who walked two and struck out eight, went 12-6 in 2007.
Jason Frasor worked the eighth and Kevin Gregg got two outs for his 31st save in 36 chances after Shawn Camp gave up a two-run single to Andres Blanco in the ninth.
Texas right-hander Scott Feldman (6-10) was activated from the 15-day disabled list before the game to pitch in place of injured lefty Cliff Lee (back). Feldman, who had been sidelined with a sore right knee, started for the first time since July 24.
Lee recently got a cortisone shot in his back after going 0-3 with an 8.28 ERA in his last five starts, and won't start again until this weekend when the Rangers host the New York Yankees.
Toronto got to Feldman in the second on Buck's homer. The ball struck a metal bar above the outfield wall and bounced back onto the field, and Buck initially stopped at second. Blue Jays manager Cito Gaston came out to argue and the umpires huddled before heading off for a video review. After about 2 minutes, crew chief Tom Hallion came out and indicated it was a home run.
Texas answered in the fourth on Guerrero's two-run shot to left, his 26th.
Toronto tied it in the bottom half on Wells' first homer, then reclaimed the lead and chased Feldman in the fifth on Jose Bautista's two-run double.
Feldman lost his fourth straight decision, allowing four runs and seven hits in 4 2-3 innings. His only walk was intentional, and he struck out four.
Toronto made it 5-2 in the sixth. Buck hit a drive to almost the same spot as his homer, but was held to a single when the ball caromed off the wall. After moving to second on an infield chopper, he scored on an RBI double by Dewayne Wise.
The Rangers cut the gap to 5-3 in the seventh on an RBI single by Blanco, but Wells went deep again off right-hander Darren O'Day in the bottom half. Two batters later, Lind connected off lefty Darren Oliver.
NOTES: Rangers SS Elvis Andrus (right hamstring) took batting practice but will not play until Friday, to keep him off Toronto's turf, manager Ron Washington said. ... Toronto extended its affiliation with Class-A Lansing of the Midwest League through 2012, and added Bluefield of the rookie Appalachian League as its seventh minor league affiliate. ... The metal letter 'B' in a Jackie Robinson sign that was dislodged by Bautista's foul ball and fell on a fan Monday had been screwed back into place Tuesday. ... The victory was the 900th of Gaston's managerial career.