One thing I thought of and tried, if I press the primer bulb down, plug the fuel inlet nipple with my finger, and let go of the primer bulb, shouldn't the bulb stay sucked down, due to no air being able to come in?
Yep... it's pulling some fuel into the bulb.not filling it up, but fuel is coming in.Press the purge bulb down and then put finger over the purge nipple and release the purge bulb. If it sucks fuel into the bulb the check valve in The purge assy is bad.
Same result as earlier.Do same test with carb turned with purge bulb on the bottom snd see if bulb fills. Pump it a half dozen times or so.
I think what is happening is the check valve on the purge outlet is bad and the engine runs pulling fuel from the purge bulb then pulls air when the bulb is empty.