They were defeated by Canada 33-20 in the 13th place semifinal.
PNG scored in the second half through Willie Tirang, Freddy Rova and Arthur Clement.
Before taking on Canada, the PNG side got thrashed by France 17-0 in the challenge trophy quarter final.
In their pool matches, Pukpuks got defeated by Australia 26-7 with Manu Guise scoring the only try for PNG.
The Pukpuks fought hard in their opening match against the Scots despite going down 26-12.
Their points came from tries to Gairo Kapana, Emmanuel Guise and a try conversion from Arthur Clement.