My 53 f100 sat for about 4 years. I was able to get the truck running pretty easily but I did need to pour a small amount of fuel into the carb to get it to start. I also noticed to that one of the previous owners actually put a hole into the air cleaner so they could prime the carb as well...making me think this has been an issue for the truck.

To further complicate things a bit, there is a **** style switch that someone labeled, "fuel pump" inside of the cab. It did not appear that it came from the factory with this...but maybe it did.

The truck ran fine once it started and I let it idle for about 25 minutes a couple of different times. Every time though, I had to prime the carb to get it to start.

Is the problem the fuel pump?

 

Likely the carb and/or fuel pump gaskets and diaphrams have shrunk from sitting dry and have developed air leaks so the pump is losing it's prime and the dry pump won't pull the fuel from the tank. Best solution is to rebuild both. While the pump is off blow the fuel line back and install a clear inline fuel filter close to the pump. That way you will be able to see if fuel is in the line, is flowing, and if the filter has gunked up.
There was no electric fuel pumps on our trucks, so the switch you have may have gone to an aftermarket pump a PO installed. You may want to trace the wires to see if the switch is still powered and or if there is still an electric pump installed. If there is a pump in the line, that may be the cause of losing the prime. If the truck was a farm truck, the farmer may have used an electric pump to transfer fuel to his farm equipment? I'd plug the hole in the air cleaner so you are not sucking unfiltered air into the engine.