D.J. LeMahieu then hit a sharp grounder to shortstop Brandon Crawford, who bobbled the ball before getting the force at second. Ehire Adrianza also had trouble controlling the ball and his relay throw to first was late, setting up Morneau's hit.
The no-decision denied Bumgarner a chance to move into a tie for the NL wins lead with nine. He allowed four runs on six hits, walking four and striking out nine. Bumgarner had allowed a combined four runs in his previous 29 innings.
Rockies starter Juan Nicasio gave up three runs on four hits over two-plus innings. He walked four and struck out two.
Nicasio could not finish four innings in his second straight start, facing two hitters in the third before giving way to Franklin Morales. He's allowed 25 runs on 35 hits over his last 15 2/3 innings, a 14.36 ERA.
Nicasio walked Tyler Colvin and Crawford to open the second inning and Adrianza singled to put the Giants ahead. Bumgarner bunted and was safe when Nicasio threw the ball wide. Crawford scored on the play. Hunter Pence also drove in a run.
Tulowitzki's 18th home run of the season, a two-shot into the left field bleachers in the third, cut into the lead but the Giants answered when Hector Sanchez and Pablo Sandovalhit back-to-back home runs in the fourth.
Sanchez hit for Buster Posey, who left the game as a precautionary measure after taking a foul ball off his mask. Sanchez's previous 23 RBIs all came in Giants' victories.
Tulowitzki, the NL batting average leader, is hitting left-handers at a .441 clip (26 for 59) this season.
Brandon Barnes' RBI groundout in the fifth was matched by Colvin's RBI single in the sixth to make it 7-3 for the Giants.
Pinch-hitter Josh Rutledge added an RBI double against Bumgarner in the seventh to cut it to 7-4.