Electric pump before or after mechanical

Smartest thing I did (before I went EFI!!) was a rear mount electric pump and a home built return system with a wix filter....built in return port. They make several sizes. AND a nice big thick carb isolator gasket.

The thing is if you PUSH the fuel to the front UNDER PRESSURE it raises the boiling point in exactly the same way a rad pressure cap raised the boiling point of coolant.

"You could" also run the electric pump (in the REAR) INTO the mechanical. When a mechanical pump reaches design pressure, the arm just floats on the cam, so it will not "add" any to the pressure already crated, unless it drops for some reason.

THE PROBLEM is that if the pump diaphragm leaks/ ruptures, the electric pump will REALLY fill up the crankcase with fuel. "Rapid expansions" sometimes occur.