Can’t figure out why I have a no-start…

So I’ve been working on bringing a wrecked 2002 R1 back to life over the last couple months to include a full engine rebuild. I finally have it all put back together but I have a no start.

I am getting a code 43 but ONLY when I hit the run button and it goes away when the switch isn’t toggled. The fuel pump is also priming indefinitely once the switch is hit and shuts off when the switch is toggled off.

From the manual I can see that this is a fuel system voltage code but where do I go from here?

Thanks for any and all suggestions, I’m not super electrically inclined but I’m trying to learn as I go.