ok, so my alternator only charges when it feels like it... there'll be times when im driving and its at 14.5 V... and sometimes its at 11.5-12.3 V... i hav an s4 chassis and running an S5 alternator... first i had the two wires ( S and L ) hooked up to the S4's R and L... but it kept draining, after some searching i found that the S should be hooked up to a constant source, so i redid that... so far no draining, but still that charging issue. had the alt. tested by autozone and they said its good... any ideas?

 

wrong pulley size? belt slipping?

 

Try and get hold of the engine electrical section of the FSM.

This has a plan of attack in it, showing step by step, voltage, resistance checks... which will lead you to the cause of the problem.

Might be a dodgy regulator...

 

is the voltage dropping during cruise? or when you are doing something that uses electricity (braking, turning *if you have PS*, turning on lights, etc)

 

the voltage readings are really just random... just got an FD dual belt pully so ima sum up some money and just get an FD alt. hopefully its just a bad alt.... LOL

 

Those autozone alternator tests suck! Mine was giving me some trouble, going in and out; I got mine tested, and they said it was all good, then it COMPLETELY died on me later that day! Get a new/used one on here for cheap.

 

Intermittent electrical failure. It happened to be good when they tested it.

Check your belt tension first (see FSM or Haynes manual) and have Autozone test your battery too (free), but I don't think either of those is the cause. After those tests get a new alternator. Don't get an Autozone/Kragen/Pep Boys/etc. alt. Try a small shop, reference from a mechanic, "new" alternator, OEM, etc. If you're forced to get an alt from a big shop, here's what will happen: You will often not be allowed to get a refund (replacement only). But still save your warranty info and receipt. Maybe you'll get a good alt the first time, maybe not. If not, your alts will keep lasting a while and then dying on you until you get a good one. Meanwhile you just keep returning them and getting replacements. I made the mistake of buying an alt based on its lifetime warranty. Fortunately I managed to get a refund after two alts blew in a row. Current alt is from a small shop based on a mechanic's reference (owner rebuilds them himself). It cost less and it seems to be lasting.

Oh, and Denso remans are supposed good but I haven't seen one for an RX-7. But if Autozone has Densos for the RX-7, that may save you some trouble. Or you could go through the buy, works for a bit, blow, replace under warranty, works for a bit, blow, replace under warranty, etc. hassle. I think I was just unlucky when I got two bad ones in a row. Well, 3, if you count the P.O.'s. Though that one did last 8,000 miles.

 

LOL... dude eric sounds like u had more problems with it then me... are u coming out on friday? i think ima just get an FD alt.