I got a 79 rx7 and just bought a new alternator from autozone. Got it all hook up and it stared to smoke so I took it back thinking it was the alternator. Got a new one and my friend who works on cars to hook the new one up and the fusible link in the motor bay stared to smoke. Any ideas what could be going on

 

Off hand I'd say the alternator output line going back to the battery (electrically beyond the fusible link) is shorted. It's not clear if it's smoking when you are making the connections to the alt and battery or if it's smoking after you start the car. BIG difference.

I will assume this is happening before starting the car.

Question 1:
Without the alt connected, but with the battery connected (be careful of the loose alt wires) do the headlights work?

1a: If no, can you charge the battery with an external charger?
If no, you definitely have a short in the main bus line from the battery or have a shorted battery.

If the answer to question 1 is yes:

Question 2:
Do you have 12V on the heavy red alternator wire terminal.

2a: If no, then the wire is pinched off or worn through somewhere on its way back to the battery and is shorted to ground.

In either of these cases you obviously have to identify the point of the short before going to yet another alternator.

I would also check the +12V line going to the starter solenoid.

Let me know what you find for these answers. Knowing them and if your still having trouble we'll go to the next level with the diagnosis.

Good luck.

 

For a quick check, I would grab a DMM and do a continuity test on all three connections at the alternator. Check for continuity to ground on both spades in the plug and the large wire.

 

Thank you its when I turn the key on that it starts to smoke thought mabey volt regulater or wiring harness can't try anything for a week

 

sorry for the very late response but it was winter, headlights do not work when the alternator is disconnected. the battery has a 12.5 charge on so that would mean a short. you said in the main bus bus line are you talking about the positive wire from the battery? and if so how do you check for a short?