[bret a ewing]

John,

The fuel supply system on the CSX4XXX is quite similar to the original cars.

Utilizing a fuel cell with 2 pickup tubes and 2 separate fuel supply lines, one from each pickup. One pickup in the fuel cell is higher in the tank than the other.
The primary pickup is the higher of the two and is fed to the carb via the engines' mechanical fuel pump.
The secondary fuel supply is the lower pickup in the fuel cell and feeds the carb. via dual electric fuel pumps. They were Stewart Warners if I recall correctly.
The reasoning was, since there was no fuel guage on the S/C cars, you would run the car on the mechanical pump until the driver noticed the fuel pressure drop on the guage. At that time the driver would flip on the electric pumps giving him a reserve of about 3-5 gallons and head for the pits or gas station.