Gangjee carded two-over 73 and that alongside his first round 67 placed him at two-under 140 and in tied 45th place, a sharp fall from his overnight 12th position.
Starting on the 10th, Gangjee birdied his opening hole, but had a roller-coaster of a ride with a bogey on the 11th, birdie on 12th and then a bogey on the 16th to turn in even-par.
On the second nine, Gangjee dropped bogeys on first, fifth and seventh and birdied the sixth.
Indian-origin Swede Daniel Chopra (71-74) missed the cut, which came at two-under.
Canada's Brad Fritsch fired a seven-under 64 and moved into the lead at the halfway point.
Fritsch is at 12-under 130 for his first two trips around the Southpointe Golf Club, one shot better than veteran Cliff Kresge (65).
Casey Witenberg carded a four-under 67 in the afternoon to reach 10-under 132 and is alone in third.