You don't say what car you have but, regardless, there should never be a black wire to the fuse box. Commonly there is a white wire from the ignition switch to one fuse with another white from the same side of that fuse goint to the pump. The other side of that fuse has a bunch of green wires. The brown wire should feed the other fuse.
Bayless
Never express yourself more clearly than you can think
'48 Prefect
'67 Sprite (project)