TimberPig, sorry can you be more specific. I am not sure what line is the impulse line.
I noticed today that if I take off the fuel cap and the put it back on the saw will run perfect for a little while. I cleaned the vent in the cap but it is still doing the same thing.
The impulse line goes from the crankcase to the carb. It operates the fuel pump diaphragm, to feed fuel to the carb.