Strizzo
Well-Known Member
The pump is in the mag carb and has a diaphragm that is moved by the pulse of pressure from the crankcase and the check valves in the carbs. It could have been damaged when your buddy had the carbs apart cleaning them, to test the integrity of the pump diaphragm, you can apply 3psi to it, it should hold for 10 minutes. The pulse line should be the only line that runs from the carb to the crankcase, and it should be about 6 inches long.