Leonard Thompson and Morris Hatalsky shared fifth place at 10-under-par 206.
The win was Morgan's first since last year's Instinet Classic, which also took place over Father's Day weekend. The victory was No. 21 for Morgan in his career on the elder circuit, moving him into sole possession of seventh place on the Senior Tour's all-time wins list.
Morgan won this tournament for the second time and has finished in the top 10 in all six starts at this event.
'I enjoy the course,' said Morgan, who won this title in 1997. 'It changes a lot and you need to be on your game. It's been a great course for me.'
Morgan began the round one shot behind second-round leader Jay Sigel and took no time matching Sigel at 10-under. Morgan birdied the par-5 opening hole to draw even and pulled ahead with a four-foot eagle putt at 6.
Fleisher and Hatalsky drew even with Morgan when they both birdied 10 but Morgan, who played behind both Fleisher and Hatalsky, got back in front thanks to a two-putt birdie at the same hole.
Morgan went up two with a seven-foot birdie at 14 but dropped a shot with a three-putt bogey at 15. He put the tournament out of reach with a pair of seven-foot birdies at 16 and 17.
'My game plan today was to not make too many mistakes,' said Morgan, who pocketed $240,000 for the win. 'I just wanted to get it close and just get into position for birdie.'
Morgan's struggles in 2002 can be attributed to his health. He had bulging discs in his neck at the start of the campaign and seems to be feeling better each week.
'I got off to a bad start physically this year,' said Morgan. 'I played well last week and my game was good coming in here this week.'
Fleisher had every opportunity to catch Morgan on the back nine at Springhouse Golf Club. He missed a six-foot birdie chance at 12 that would have tied him for the lead and then missed birdie tries at 13, 16 and 17.
'I had opportunities,' said Fleisher, who is still winless on tour in 2002. 'If I made some putts it might have been different. I missed a lot of chances.'
Fleisher has been embroiled in controversy all week. As last year's U.S. Senior Open winner, he received an invitation to compete at the U.S. Open this week at the Black Course at Bethpage. After playing there a few weeks back he decided he would not accept the invitation to play, feeling he would have no chance of competing.
'It was my choice to not play the U.S. Open,' said Fleisher, who shot a final-round 69. 'I don't think they should take the spot away from the Senior Open winner.'
McCullough shot a 68 in the final round while Quigley, the Senior Tour's 'Iron Man,' posted a 69.
Fuzzy Zoeller, who won last week's Senior PGA Championship, tied for seventh with Bobby Wadkins, Butch Sheehan and Rodger Davis. The group finished at nine-under-par 207.
Sigel struggled mightily down the stretch Sunday with four bogeys in his last five holes. He shot a four-over 76 and tied for 21st at minus-six.