Waller had runs of 36 and 38 yards on his way to a ninth career 100-yard game. Olsen scored on both of his catches, finishing with 35 yards receiving. He has 15 career receptions, six for touchdowns.
The Bulldogs scored 27 straight for a 34-7 lead.
Abilene Christian tied it after Fresno State's opening-drive touchdown with an eight-play, 49-yard drive capped by Herschel Sims' 1-yard touchdown run. But the Bulldogs retook the lead on the ensuing possession and held the Wildcats scoreless until an ACU touchdown on the final play of the game.
Fresno State visits No. 17 Ole Miss for its next game on Sept. 12.