Rebuilt Thermoquad issue -- It has to be primed before start each time

Maybe it is just the the acc pump well that is losing its prime. Or maybe you have a piece of debris in the acc pump well. There is a check ball in the bottom of that brass disc. if it is getting dirt in it or in the discharge orifice and you step on the throttle a lack of pump shot will cause it to stall. I would tap the acc pump back out and blow out the check ball with carb cleaner then air. And while you have it apart, run a small drill bit through the cast discharge hole that the hose connects to. Take it apart over top of a whit rag, so you can see if any debris falls out. Double check the acc pump well seal while you are in there. It is not on upside down is it?