The win was sealed three minutes out from full time with a try to halfback Watson Boas in front of another sell-out crowd in Port Moresby on Sunday afternoon.
It was the Wolfhounds who opened the scoring after four minutes through hooker Michael McIlorum, who scored after Kumuls captain, David Mead, failed to ground the ball in the in-goal area.
After dominating possession, the Kumuls finally got on the board ten minutes later.
The first try came from some razzle dazzle football which created space out wide for a barnstorming Gary Lo.
Lo still had some work to do but made it look easy, shrugging off six defenders to cross over.
The Western Highlander proved a handful for the Irish all afternoon and played a hand in the second try with a break that brought the Kumuls within striking distance.
Five-eighth Ase Boas this time went right, drawing in the defence on the fifth tackle before flicking it out to a flying Nene Macdonald to do the rest.
Two unsuccessful conversions from Rhyse Martin left the score at 8-6 at the break.
It was the Irish who had most of the possession in the second half.
It was an error riddled second forty minutes of play from both side, but the Irish came close to taking back the lead on numerous occasions.
However, the Kumuls stood up to the test with some desperate defence to keep their opponents out.
It was a thrilling last ten minutes - forward Louie McCarthy-Scarsbrook came agonisingly close to stealing the win for Ireland, knocking on over the goal line.
Next it was Kumuls flyer Justin Olam who thought he had the match won, crossing over, only for the last pass from Ase Boas to be called forward.
An error from Kyle Amor gave the Kumuls the win as Watson toed the ball to regather and score near the posts with three minutes left on the clock.
His brother, Ase, did the rest, adding the extras to leave the crowd of 14,800 in a frenzy.
“Full credit to the boys. Our defence got us through. There is still a lot of work to be done,” said Kumuls coach, Michael Marum.
Ireland coach, Mark Aston, said: “It was a great game. We’re disappointed. We believed we could win it. The boys took it to the Kumuls.”
(Nene Macdonald flying over the line for the Kumul’s second try)