Mechanical fuel pumps have check valves that allow fuel to pass with about a pound or 2 of pressure.
On the old KT/magnums, after setting a while, the carb bowel goes dry sometimes as it sits right above the engine and heat soaks.
Soo if you remove the fuel cap and blow in the tank with lung pressure it will fill the bowel with fuel and allow quick starting and reduce long cranking times,
if your ears are good and it is quiet, you can hear the fuel entering the carb and the air escaping from the bowel as you blow (I have to use my hearing aids)
If your mechanical fuel pump is good, you don't need an
electric fuel pump,
as it is just a band aid on a problem.
I'm not familiar with an
electronic fuel pump so I don't know how they are constructed.
