The Dolphins defense turned in a pretty solid performance in the first half until an 85-yard drive culminated in a touchdown pass from David Garrard to Ernest Wilford to make the score 14-3.
Jacksonville had taken the lead 7-0 in the first quarter when David Allen returned Matt Turk's first punt of the game 76 yards for a touchdown.
The Jaguars increased their lead in the second half with a pair of field goals and a touchdown pass from third quarterback Quinn Gray to first-round pick Matt Jones.
The Dolphins offense was hurt by a couple of turnovers, an interception by Feeley and a fumble by Lamar Gordon on the first offensive play of the third quarter.
The Dolphins dropped to 0-2 in the preseason. Their next game is next Saturday at Pittsburgh.