I have been thinking about this a little more, and I wondered about a return setup. My 70 Chevy Impala had such a setup and it seemed to work good. The fuel filter had a small line leaving the filter which returned to the tank.
Another idea I had would be to place a normally open solenoid vavle in a fuel line running from the carb inlet to the inlet of the fuel pump. When the ignition is switched on, the solenoid closes and the fuel pump pressurizes the line to the carburetor inlet. When the ignition is shut off, the solenoid valve opens and allows the pressure in the line from the fuel pump oulet to the carburetor inlet to pass into the fuel pump inlet line. Two problems came to light with this--I haven't found a 12 volt normally open solenoid valve and the fuel bled off has to go to into the bottom of the tank, which would not relieve as much pressure as dumping into the top of the tank.
Another thought was to install an electric fuel pump, which would be shut off before shutting the engine off. The electric fuel pump would be controlled by the ignition switch, while the ignition coil would be fed from a 117 Murphy engine protection switch. To start the pickup, turn on the key (which starts the fuel pump filling the carb), hold the Murphy button in (which feeds the ignition coil), and start the engine. To shut down the pickup, turn off the ignition, which kills the fuel pump. When the engine dies from lack of fuel, the Murphy switch will detect that the engine has lost oil pressure and will kill the ignition circuit. Again two downfalls to this plan--cost of a Murphy 117 switch and a murphy gauge or low oil pressure switch and wasting gas idling to empty the fuel bowl every time.
On a side note, would it be a good idea to run the bypassed fuel through a cooler so the fuel in the tank will not get too hot?
