I have an 86 non-turbo rx-7. I recently swapped in a motor from another 86 into it and can't get it to run properly. No matter what I do, the battery keeps dying. I tried a new battery, like 3 different alternators, looked at wiring, etc. For some reason it isn't charging. The car will run fine for about 5 minutes and then the battery dies. I don't know what to do.

Start by throwing an amp meter on the battery and disconnect fuses and relays until it goes to 0. Then you know what is drawing and draining the battery.



Either start checking things there or start replacing.



Much easier to know about where to look than checking over the entire car.



Good luck. https://www.nopistons.com/forums/pub...IR#>/smile.png

Check your grounds.

A friend of mine had the same problem on a 91 N/A

went over ALL the ground wires, it's been fine since?

I just did a swap like that to but from an 88SE to an 86 Sport. I was also having that no charging thing at all. So I added a 4 gauge wire from the positive of the battery to the alternator, and from my ground strap to the front bolt on the Alternator the one you use to tension. Now the voltage does not go below 14 on the meter! If you dont have a ground strap go str8 to the battery - that should help if that dont work then you got a serious problem ! If you got a new Alternator and a battery then there is some major draw on the car to kill it in 5 min.



Just my $.02



https://www.nopistons.com/forums/pub...1047683894.gif GROUND STRAP's https://www.nopistons.com/forums/pub...1047683894.gif

(even the cheap ones)

I am going to try the ground straps. Either I forgot to put one in or there must be a problem in the harness itself.

i dont think anything on the car with everything possibly turned on and you revving the **** out of it would drain a new battery in five minutes, something is seriously wrong, do you have any kind of system hooked up to the car? like evyone else said check/replace the grounds, have the battery charged to full, did it die in 5 minutes the very first time the battery was installed? if not its dying so quick because theres not really any juice in the battery anymore. i wish i could help more https://www.nopistons.com/forums/pub...IR#>/bigok.gif

just a penny here, i had that until i cleaned my battery terminals