Lum’s first three scoring passes went to Ryan Spadola, who had nine receptions for 214 yards. Lum’s fourth TD, a 2-yarder to Sean Farrell, gave the Mountain Hawks (2-1) a 27-9 lead with 11:11 remaining.
Lehigh built its lead to 34-22 with a 10-play, 61-yard drive ending in Keith Sherman’s 2-yard run with 1:54 left.
Princeton then drove to the Lehigh 10 but lost the ball on downs with 20 seconds remaining.
Lum, who came in as the Football Championship Subdivision’s No. 3 passer, completed 28 of 38 with no interceptions.