Voltage drop

Car idles fine. Runs fine. As soon as I turn on nitrous fuel pump. It’s drops to just about 12v on the dot. All my grounds are good and tight. The relay is working fine. All my connections are good. Can’t find the problem
Please throw those ideas this way. It drops basically a full bolt. From just over or around 13 down to 12. When I turn on the fuel pump for carb not nearly as dramatic of a drop. Maybe .3-.5 volt drop with the other. ????