[luvbowties]

Originally Posted by 63burban4x4

X2. IIRC, the fuel normally is drawn into the carb barrel by the venturi effect. Air rushing down the barrel past the venturi, draws fuel into the airflow. When you stomp the pedal, the throttle plates instantly allow more air, but it takes a second or two for the venturi effect to provide more fuel. The accelerator pump overcomes that momentary lack of fuel with a little extra fuel "pumped" in, That little squirt of fuel provides enough fuel until the venturi effect takes over. Easy then to understand the "stumble" , if the accelerator pump isn't working. It's been a while, but I think the accelerator pump has a rubber diaphram, which is pushed down by the accelerator pump linkage, pushing a little fuel in front of it. That rubber plunger can dry out, crack, and fail. At least that's how I remember it...LOL. The real mechanics here can correct me if I'm wrong.

Dunno why you mentioned "real mechanics" above--sounds like you gave quite a good & thorough explanation of just how it works!