5/16 in line fuel check valve

Pretty normal with today's puppy pee gas but you may have a problem. Checking for accelerator pump squirt would be my first test. If you have none the carb is empty. Before you crank, disconnect the fuel line somewhere convenient between the pump and the carb. I unhooked the filter because the line doesn't have a barb or a flare there. Connect a rubber hose to it with the other end in a quart jar. Crank the engine a few seconds. If you get fuel right away there is no fuel system issue and the gas didn't "drain back" into the tank. You didn't mention anything about your engine, intake, carb or the like but all combinations can get hot enough to boil the gas out of the carbs after a hot soak. Stock cast iron manifolds are worse. Edelbrock/Carter carbs are worse than Holley's. Holley 4160 carbs (with the fuel tube between the bowls are more susceptible than double pumpers.) Thick base gaskets help. Many have added a electric charge pump near the tank with a momentary pushbutton switch to fill the carb before starting. That works well I have heard.

View attachment 1715754248

View attachment 1715754249
My very thoughts
Iron head 340 Edelbrock aluminum intake, pump and carb with thermal base gasket. 93 octane pump fuel no ethanol.
First thing I did was to replace the accelerate pump, when I took the top of the carb it was almost dry no fuel in the pump well.
Just seems like it should not take so much time to pump up fuel, somethings not right.
And yes Mike I agree that our crappy fuel has something to do with it.
As a side note a friend has a 1969 Century boat with a 440 and a very old carter AFB that thing can sit for weeks with crappy old fuel and it will fire up in 2-3 seconds of crank time. Points ignition