So Im in the process of building a custom wire harness for my race car. I was going over the factory diagram and noticed they had two relays in parallel for the fuel pump. Why is this, and do I need to do the same for my harness? If it makes a difference Im running a Walbro 255

 

Heres a diagram of what Im talking about

 

Those are in series. I would guess for safety, the first is on when the ign is on and the second is ecu controlled. You could technically ditch the first one. I'm not sure what the third one does, maybe some type of primer.

 

You only need one relay for the pump. I believe that is a safety factor if something happens to the engine function the fuel pump shuts down. In your case for a race car you will need a shut off switch in the back that will kill all the electronic systems. If you relocate the battery to the trunk it is easier to run the switched power with 18ga wire and put the relay in the back near the pump and reduce the distance of the 10ga power wire to the pump.