I have an in tank walbro pump that I need to wire up(for my potential EFI conversion). From the spec sheets I have seen that it draws 5-7 amps. I will have to run a wire to supply power from the firewall(or so) back to the pump. What gauge wire should I run considering that it must be about a ten foot run? Actually how do you figure the gauge size based on amp draw and length of wire?