I've just bought a Danarm hedge trimmer fitted with a Kawasaki KT12AD 2-stroke engine and mine is also behaving in the same way. Judging by the length of time it runs, I suspect the diaphragm in the carb is punctured. If I manage to locate a supplier for a carburettor repair kit I will post the details for you. Otherwise it's a question of making a diaphragm...
AiredalePete, September 2010