The 25-year-old won the tournament in 2012 but a year later walked away midway through a disastrous first round.
He returned to Palm Beach in 2014 and went to a play-off – which he lost – but Thursday saw him end the day eight shots off the pace being set by the clubhouse leader, with two birdies on the last two holes of the day keeping him afloat.
Having won the Dubai Desert Classic and taken four second places from five, McIlroy’s hopes will have been high but he was forced to take a backseat in Florida.
The tone for his day was set with a double-bogey on the first hole and, despite pulling a shot back on the par-five third, he bogeyed the fourth and then added a second double of the day on the fifth.
He trimmed a shot back on the eighth with a three-shot birdie, but was unable to get a run going and was soon back to four over come the 11th.
His malaise continued to the 14th with another bogey, before a shred of hope with a fine two on the par-three 17th followed by another birdie at the last.
When McIlroy signed his card he was eight shots behind leader Jim Herman, who had long since recorded a five-under 65.
The American was trailed by compatriot Brendan Steele on four under, with McIlroy’s former Ryder Cup team-mate Padraig Harrington on three under alongside Martin Flores.
Patrick Reed was also three under after a real see-saw day. The American went to the turn at four under but a run of four bogeys over the next six holes – with a birdie thrown in too – dropped him to one under.
He recovered his composure, though, and signed for a three under courtesy of birdies at the 16th and 18th.
Germany’s Martin Kaymer was one of a cluster of players on two under, while Ian Poulter and Lee Westwood were one over, along with Phil Mickelson.
Rickie Fowler was even while Graeme McDowell had a day to forget, ending four over par.