I had that problem in the 80s, but my battery was under the hood. The heat caused the a plate in the battery to warp and short. Replaced the battery and was good. Obviously isn't your issue. Good Luck.
My battery is reading 12.2, I turn on my headlights then turn key and headlights go off. Hmmmmm that buzzing is starting to annoy me
Bad, discharged battery, iffy cables or excessive current draw... BUT if battery battery and cables are good you should be seeing smoke from the current draw... Measure voltage on batt post(not cable), if it's dropping more than a couple volts it's a battery problem...
Those grounds need to be clean metal to meal contact...Paint/rust are great insulators... That ground cable end in the trunk looks like crap...Cable looks dirty/corroded at that end too...
That sound like a ground issue to me. You would be amazed how important it is the have a perfectly clean mating surface for the ground. Try moving the trunk ground maybe to the trunk latch bolts or a bolt through the the frame So it contacts both sides of the frame. PS nice looking Mav. I really want a EFI in mine too.
Thanks! Alot of hard work. Means a lot! I'll be busting out the wire brush tomorrow to tackle those grounds. I'll report back
UPDATE Yesterday I took off my block ground and battery ground. Took the wire wheel to all contacts replaced an ate up battery terminal. Wire wheeled all the paint away at the two parts on body for good ground. Made everything nice and tight. Well the buzzing went away but still no turn over. Just rapid clicks. So I tested the battery. Sure enough it was 12.4 but once I started cranking it dropped down to 6.2ish. So I thought it could be my battery or Napa starter. I took my interstate battery out of the toyota. Tried that. Buzzing came back lol. After that the new starter solenoid got here from summit. Because I wanted to switch back to old style solenoid I originally had. Hooked it all up. Tried turning key again. This time the starter just spins and does not engage... idk anymore lol new starter maybe ?