Sometimes my car will start, sometimes it wont. I have a 86 IROC with a swapped 350 carb. Battery and Alternator tested fine and show it works. Just Replaced the Starter and still the problem is there. When it doesn't start, it still shows full battery and everything turns on and works with the key at run, but when i go to turn it over there's nothing. No click or anything! I can jump the starter and it spins. So im lost. I haven't found a rhyme or reason on how i can get it to fire up. After messing around with everything it will finally start.

Any ideas. Is there a relay somewhere or something.

 

Might be neutral safety switch - if it's an auto, it's on the shifter, if it's a manual, it's on the clutch. I know the auto is adjustable, might try adjusting it before replacing it.