Nice page: New guy with problems
 

First of all let me say that I have been on viewing mode for quite a bit of time but never posted, so here it is.

I own a blue 1986.5 Toyota Supra non turbo and live in NJ. I got this while I was working driving tow trucks and it didn't pass inspection for a bad ball joint. A few hundred later and I am the proud owner. The Supra is stock, but needs a few things (A/C has leak and radio works but doesn't receive.) It has 108k and still has a working TEMS system that I am debating whether to take off or not.

The problem I have is that it has no power when I turn the key. The only way that I can get it running is to jump it. Once it is jumped it runs great and keeps running. I assume it is not the battery due to this, maybe the neutral safety switch?

Mods I plan: Clear turn signals (if someone knows where to find them), Aluminum rims, led lighting (inside and underneath) and double din stereo with nav.

Battery starts the car, alternator keeps it running.

Does the car crank at all or even make a click when you try to start? If not the two first things I would check are the clutch start switch (the clutch has 2 switches, you want the one mounted to the firewall) and the stock alarm; lock the doors with the keys, make sure the "Security LED" lights up, wait one minute and unlock the door with the key.... might try unlocking via the pass door or the hatch as the switches tend to go bad when they're this old.

Car is an automatic, so it has a neutral safety switch.

Car does nothing when I hit the key, no power at all. When I hook the cables up to it, then it will light up and start. It will run after that forever.

Sounds like you have a bad battery and if you keep running it like that it's gonna take the alternator out shortly after. Take your battery out and go to your local auto parts store; they should be able to test it for free