[Kube]

Couple of things...
1) these carbs are open to the atmosphere. Evaporation at work.
2) Fuel pump is not working properly. There is a check valve within the pump that prevents fuel from flowing "backwards".

I tend to pull the choke out when I shut a car down during summer driving months. that does slow down the evaporation.
My '36, during winter storage, is started once per month. I simply make certain the choke s pulled out, pump the throttle a few times and hit the starter button. Within ten seconds tops, the engine fires.
Both the fuel pump and carb were rebuilt by Charlie Schwendler.