4ac Electrical gremlins - No power sometimes, unhooked battery clamp/fuse box, suddenly power?

[undercoverninja]

Probs going to have to get an auto electrician to have a look, but my ae71 4ac gets power to the starter/interior loom only very occasionally, it will start some days and not others. I moved the fuse box once and it suddenly started working (had power to the interior, and I cranked it and it started), then after i stopped running it, and tried again a hour later, it was back to not working. Any wiring diagrams or something I can have a look at? Wiring sucks so much ass.

It's a molested ae71 4ac, so the looms probably been fucked with, as a aftermarket fuel pump and weber carb have been installed.

I have shit all experience with auto elektrics, so any basic pointers or steps to trouble shoot/wild guesses on the source of the problem would help too lol.