Hi everyone,

so I was having some fun with my '86 fc yesterday evening in a parking lot. I was with my girlfriend and I stopped for about 5 minutes to talk (without turning off the car).
It was really hot so the AC was on at about 90% strength. After about 4 minutes, I noticed the car loosing "power" (the dash lights were getting darker, headlights were slow to pop in and out, etc.). So, I turned off the car and now it won't start, it doesn't even crank, so I guess that the battery is dead ?...but why ???

I know that the guy who had the car before me changed the alternator for one from a FD, could that be the cause of the problem ?

thanks.

 

Using the AC can drop idle speed. It's not supposed to, but it does happen. If the FD alternator conversion was done with a pulley that is oversized, the alternator will struggle to charge the battery at low RPMs. You can measure the inside diameter of the pulley to get an idea if it is in fact an underdrive pulley. It needs to be about 45 mm ID, but there are some available that are larger. I have one that I used for a short time that was 54 mm ID, and I replaced it soon after.

 

sorry to revive an old thread but I just removed my alternator in order to replace it for a new one and I was wondering if you could tell me if this is an OEM FC or FD alternator ? Also, I measured the pulley and it has a diameter of about 70mm...




thanks!

 

For sure it's not from an FD! Pretty sure is a oem FC alternator!

 

I confirm this isn't an FD alternator.

 

looks like an S4 Fc alternator.The connector plugs in at the back and is like a T,..right?
The s5 has a connector up top,somewhat like the FD plug connection.

 

Yeah, it looks like an S4 alternator or earlier even. That pulley is huge compared to the OEM S4 pulley.

S4 alt: https://www.rx7club.com/album.php?al...pictureid=6188
FD alt: https://www.rx7club.com/album.php?al...ictureid=21609

 

alright ! thanks guys.

@RotaryRocket88: could my electrical problem be caused by the pulley being too big? Where could I buy a smaller pulley? thanks !

 

Ok, so I just bought a new alternator, haven’t installed it yet though. However, while browsing through the files that the last owner gave me with the car I think that I might have found a new piece of the puzzle…

I found these 2 pictures:






Anyone know why he would need such pictures :S ? Is this a common mod or something ?

I know that he had a pretty big audio setup (sub, amplifier, etc.) that he uninstalled before I bought the car from him. Maybe there's a problem somewhere in the wiring and this is what's causing my battery drain ?....