Lol, as I was typing you posted photos. Your hobbs switch is self contained, the only way to test will be to get a multimeter. My guess is that it's a relay issue or possibly a defective Hobbs switch if your wiring is 100%.
Also In your photos the wires going to your fuel lid look normal? It's hard to tell by your photos, but hopefully the wiring in your tank are fuel grade wiring otherwise the wiring insulation will fall off from the gasoline. If you bought a stage 3 kit from a reputable vender then you should be good, I know my fuelit wires say gasoline resistant on them.
Did you buy a vender stage 3 kit? A vender wiring kit? Or is this all diy?