It was Purtzer's first Champions Tour title.
Playing with Morgan in the final group, Purtzer had five birdies, three bogeys and the clutch eagle en route to a 4-under-par 68.
It was the first win in 27 Champions Tour starts for Purtzer, who won with a 36-hole total of 9-under 135. His opening-round 67 on Friday featured a hole-in-one, four birdies and a bogey.
The tournament was reduced to two rounds when rain wiped out Saturday's play.
Purtzer earned the $225,000 top prize and claimed his sixth win as a professional. He had five during a 25-year PGA Tour career, the last coming at the 1991 NEC World Series of Golf.
Morgan led after an opening-round 65 and played the front nine in 2-under to maintain at least a share. He fell a stroke back with a bogey at the 11th, got it back with a birdie at the 15th, took the lead when Purtzer bogeyed the 17th and lost the tournament at the 18th.
The 1997 winner of this event, Morgan settled for his second runner-up finish in five starts this season.