mcculloch chainsaw help?

the hose that runs from the crankcase to the carburetor deteriorated and broke. can the engine run w/o this? does the hose provide air pressure or vacuum to the carb, or is it just a vent? I can't get the engine to run w/o putting gas directly in the carb intake, then it starts, but dies quickly from fuel starvation. the fuel line is clear and doesn't have fuel in it. I removed the filter to eliminate any possible plug. also, the primer line is busted. any hope for this machine?
John.