That’s interesting. I grabbed a nice snowblower from the owner as I was at my town dump. He said he had teouble starting it. Investigating at home, I had a hard time too. Turns out the primer line was rotted gone. Jury rigged a new line, fired up in two recoil pulls.Yes, CHOKE. With the choke closed, intake vacuum caused by the piston going up is presented to the engine end of the carb, pulls the fuel chamber diaphragm down and opens the inlet valve. It's this suction that pulls fuel up the fuel line and into the carb, through the fuel pump and through the inlet valve to the fuel chamber. Does the same thing as the primer, just takes longer to fill the carb, especially if the saw has a long fuel line. At cranking speed the output of the fuel pump is insignificant, it's all about the choke.