A late Garry Fleming strike rescued a point for Dumbarton but a draw leaves both sides dangerously close to the relegation zone.
Dunfermline dominated early and almost went ahead when Kallum Higginbotham’s audacious dipping volley from 30 yards clipped the top of the bar.
It sparked a period of control for the visitors for whom Nicky Clark had two efforts in quick succession, neither of which was on target.
Then the lively Higginbotham cut in from the left touchline and tested Alan Martin with a firm shot.
Dumbarton continued to defend resolutely and Gregor Buchanan summed-up Sons’ never-say-die approach with a crucial defensive header that prevented Clark getting on the end of Higginbotham’s dangerous cross.
Having soaked up the pressure, the home side broke upfield to stun the Pars with the opening goal.
The visitors failed to deal with a ball into the box from the right flank and Robert Thomson pounced to set-up namesake Joe, who stabbed the ball over the line from two yards.
Dumbarton dropped their guard on the restart and paid the price when the unmarked Clark headed Jason Talbot’s cross home.
Substitute Joe Cardle went close twice in quick succession as the Fifers seized control.
And their pressure appeared to have paid off when Clark’s shot rebounded from a post and Cardle followed up to score.
It looked like being decisive but the Sons refused to throw in the towel and got their reward when Fleming found space to score from 14 yards.