I want to run a 2 1/2 gallon fuel cell that will be placed in the open space on the other side of the battery in the engine compartment(for 110 octane to run with nitrous). I will be running a Carter p4594 fuel pump for this fuel cell and a mechanical that I have or a electric if I can't use a mechanical for the regular fuel tank . I was going to run these both to a T right before the carb . Do these have to be run separately and not both together with my carb.(pressure problem) I have a gauge and would know quickly no matter what I did , but saving time is OK also, anyone with experience with something like this.

 

If I understand you correctly, you would at the very least need check valves in each line.
Otherwise if the fuel pressure from the TANK pump were to become higher than the FUEL CELL pump, you would then fill your fuel cell with regular gasoline and possibly overflow the cell and spill fuel in your engine compartment. Guess what happens next?
I think what you really want to use is a fuel selector valve - switch over to the high octane fuel before you want to use the nitrous.

 

I know about the order of the fuel pumps so one doesn't over ride the lower pressure one, series and parallel . the fuel cell has a higher pressure fuel pump But i will use a electric shutoff valve for the pump for the big fuel tank before I turn on the pump for the fuel cell.
I shouldn't have put in the concept of running them together I was just told that you can and I wanted to know how they did it.
I can run two shutoffs one for each tank but do I need to with the pump for the fuel cell not running until I turn it on. can it push through a none running pump. . The p4594 pump can be run deadhead or not. I also have to many switches at this point to turn on and off to switch over to nitrous, maybe I can simplify the wiring