93 Z28. The car only starts when battery's charged 100%, at least 12v showing on the meter. Sometimes, it has no prob at all. Sometimes, it just won't start and I've to recharge the battery till 100%. Help!

 

Take your battery in to get load tested. It could have a bad cell.
If the battery checks out ok, then check your voltage output at the alternator when the engine is running.

 

It would not be something that simple. I've more than 30 cars on my property, needless to say how many good batteries I have. Here is the odd thing.

A fully charged battery, tested 100%, once it's put into the Z28, connect to the ground and the positive, no start. Test the battery again, only 17% left. Disconnect the ground and positive, test the battery, 95-100% again. Then connect the ground only, test the battery, 17% once again. Something in the car is draining a lot of amps, what is it, I don't know.

The wired thing is, the car will start no problem for a period of time, and then one day it just won't. And maybe another day later, or a couple of hours later, it will start again. BTW, already tested the ICM and coil, they both good. When no start, there's power going in the coil, but nothing coming out.

Any idea?

 

clean all your connections. get the wire brush out and brush the heck outa the cable ends, then turn to the power junction box (small red plastic box on the passenger side fenderwell) and take the wires lose and brush the heck outa them, then theres the ground junction right next to the power junction box, clean them as well. you a few grounds on the motor, one on the side of the block by the starter, one under the belt tensioner and one at the front of the block on the driver side. check all for corrosion or bad wires or connectors. there is no way a battery can be discharged by hooking up one side, be it positive or negative so you may have a bad tester. im assuming this does the same thing with different batteries. then check the starter to make sure the wires that go to it are tight, good and are clean. make sure the starter is bolted up tight as well. it has to ground to the block so if the bolts are lose it may get a ground or it may not.

 

Well, I've cleaned all the ground on the top or wherever I can see. The one underneath the tensioner has been tested, no prob there. The only one I've not checked is the on the side of the starter. When I try to start the car, the engine will spin at a normal speed, so I assume that starter is OK. I am just not getting spark out of the coil.

My meter is working no prob. I put the same battery in other cars, it's tested more than normal, will not drop to 17% at all. That only happens in the Z28. Like I get more than enough juice out of the battery, and then somewhere drains a lot of it, by the time the current reaches the coil, barely any left.

 

in order to drain a battery that fast it would spark when you hooked it up. have you tried pulling the fuses, all of em and see if it drains. the alternator will drain the battery if the voltage regulator inside it goes and does not disengage. also the ignitoin switch may not be turning the alternator off, should be a small wire that plugs into the alternator, thats the exciter wire and when you turn the key on it should have power to it, it should not have power to it when the ignition is off.

 

I got it start again. After the last try starting failed, my friend and I stood by the car with the hood open and just talked. All of sudden, there was a small click, sounds very mechanical, just a little clear click that came from somewhere. We kind of looked at each other and then went to turn the key and it started right up.

We believed that small click has everything to do with the no start, but we don't what it is. Now, the battery will not drain that fast either. Could that be a stick relay or something. I'd really like to find out.

 

that sure sounds like a relay. or i think there is a curcuit breaker on the igntion in the fuse box under the hood thats suposed to reset itself. im thinking the motor would not turn over if its tripped though. did it come from under the hood?

 

Yes, I think it's coming from under the hood, but it's just my assumption since it was a small sound and kind of quick. I just don't want it happen again. Every battery I've tried on this car is good, when the car is not starting, the battery will have a very low stage as long as it's hooked to the car. Once it's off the car, the battery goes back to normal. That's the odd part I don't get. Now, since the car starts, I don't really need a 12v to do it.

I am thinking there's something shorted the circut, see if it's a relay it might do it when sticking. Another question, should the replay be hot or warm while the car running? I use my finger to tough the top of each relay on the driver's side. 2 of them are kind of warm, the rest of them are cool.

 

I hate electrical problems !

http://www.z28.com/LyleA/93-02%20%20...s%20Manual.pdf

http://shbox.com/1/schematics_wiring.html

Good Luck !!!

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