Pooley stands at 3-under-par 141 where he is joined by Carl Mason (71), Mark McNulty (69) and Pete Oakley (68).
Eduardo Romero (75), John Chillas (75) and Jim Rhodes (77) were the first- round co-leaders with Pooley. Romero and Chillas slipped into a tie for eighth at even-par 144, while Rhodes fell to plus-2 and a share of 13th place.
Tom Kite and Bill Longmuir each posted a pair of 1-under rounds of 71. They were joined in a tie for fifth place at 2-under-par 142 by Senior Players Championship winner Mark James, who shot a second-round 70 in windy, rainy conditions.
Pooley looked to take control of this championship with his early play, but he tumbled back to the field. He dropped in back-to-back birdies from the second to get off to a hot start.
The 52-year-old Pooley then birdied the par-4 fifth to climb to 6 under and three shots ahead of the field. Things quickly turned for the worse however.
Pooley dropped a shot at the sixth and faltered to another bogey at the ninth. He settled down to par his next eight holes, but a bogey at the last dropped him to minus-3.
Mason, the runner-up to Tom Watson last year, picked up a birdie at the par-3 third to go along with nine pars over his first 10 holes. He then birdied the 11th, but struggled to bogeys at 12 and 14. A birdie at the 16th at Royal Portrush Golf Club moved the Englishman back into a tie for the lead.
'Leading up to this week, I was a little wary of my back and I wasn't quite swinging it the way I should have been,' said Mason. 'I was protecting it a little bit, but thankfully my good friend, Derrick Cooper, got me back on track this week with some swing tips and at long last I feel like I'm swinging the club properly.'
McNulty opened his round at even-par and burst out of the gate with birdies at the first two holes. He ran off six straight pars before picking up his third birdie at the ninth.
Around the turn, the Irishman birdied the par-3 11th. McNulty climbed to 5 under with a birdie at the 15th, however, he faltered to bogeys at the 16th and 18th to drop back to 3 under.
'I think if you take the whole picture, if somebody had said to me playing the first hole with the way that the showers were coming in, that I was going to shoot 69 then obviously I would be delighted,' McNulty said. 'But all us golfers are in the same league, we all bitch and moan about things. I was obviously disappointed to finish with three fives, but that is golf.'
Oakley used a hot front nine to climb into contention after an opening-round 73. He ran off three straight birdies from the second to jump to minus-2.
The 1999 PGA Senior Club Professional Champion reeled off five straight pars before a birdie at the 10th got him to 3 under. The rest of Oakley's round was up-and-down.
He bogeyed the 11th, but came right back to birdie the 12th. After bogeying the par-5 13th for the second time in two rounds, Oakley birdied Nos. 14 and 15 to get to 4 under. He fell back into a share of the lead with a bogey at the par-4 16th.
'I played well and did not get too nervous,' said Oakley, whose brother, David, plays on the European Seniors Tour. 'I have never been in this position before and it was gratifying to come through and play well instead of folding up my tent and going home.'
Tom Watson, the defending champion, has been battling a shoulder injury, but made the cut after rounds of 75-74. That put him at 5-over-par 149, where he shares 33rd place.
The cut line fell at 9-over-par 153 with 70 players qualifying for the weekend.