Had this same problem. Put new fuel lines on. Found the problem. Part needed is a diaphram assembly metering. It is a diaphram on the bottom of the carburator. You have to take off 4 screws to remove the plate covering it. The diaphram should not have any holes or cracks in it. Found a web site that has a parts break-down and parts list.
http://www.oscar-wilson.com/MANUALS/MCCULLOCH/211703-03.PDF
Phone number of the parts place: 606-678-9623 Good Luck!
Tom
November 2009