I bought a 94 f150 ford that has a flip switch that has to be on in order for the truck to start?

I bought a 94 f150 ford that has a flip switch that has to be on in order for the truck to start?

Added (1). The wiring runs from the battery to the cab and then back to the fuel pump wiring. I have No idea what it is there for or why it is there. But w/o the flip switch in the On position the truck Will Not Start.

Sounds like something someone's " rigged - up "… For some unknown reason.

It's there because there was a problem with the fuel pump circuitry, the wiring has a short or a fault somewhere and the person decided to just bypass it rather than fix it properly