Worked on a little Mac 3200 today. Needed new lines and the primer bulb seemed pretty shot too. Put all new in, and was surprised when the new bulb wouldn't pull any fuel? Made bubbles, and I think I can hear it sucking air from the carburetor, but won't pull any fuel. Thought I had it messed up so I reversed the lines, same thing. Its really weird. Figure it must be a check valve in the carburetor. Tried another older primer bulb too, also same. Didn't think it would run but I gave her a few pulls and off it went! Ran pretty good too for not being run in who knows how long. Had to crank the idle up 2 full turns to keep it going good. Carb looked fine inside btw, pretty nice & clean, and both diaphragms were in good condition. I was surprised that it ran, but then I don't know a great deal about how exactly the primers work. It's a zama carb. Just thought I'd share my experience because it was really unexpected.