I just put a new battery in my 94 Formula about 3 weeks ago. The tech said the alternator was okay.
It seemed to be running fine.
The car sat for a few days over Christmas break. I went to start it the other day, and just got click-click-click-click.
Lights & radio work, though the voltmeter read under 13 amps.
It did finally start with a jump.

I went to start it the next day, and got the same thing, only this time it was a very weak starting sound. It finally started on the third attempt. Weakly, I might add... almost like it was running out of gas.

Occasionally, my Security dash light will be on, and I have had recent problems with it not starting because of that (cleaned off the key, let it reset and it started)
Both of these recent instances were with my 'good' key, so I don't think it's that.

Brand new opti and plugs last spring.

So, what am I looking at here? Starter? Alternator?

A quick way to check the alternator. Once the car is running you can take flat blade screw driver and touch the back of the altermator in the very center and there should be a magnetic draw to the screw driver. No magnetism,it's not working.

I've had Auto Zone check a few before for me and they were wrong.

Check the simple things first. Are the battery cables clean and tight? GM side posts are known to loosen by themselves over time. Is the alltenator belt tight? Since the battery is new will assume it is good. Should have a min. 12.5 volts static(engine not running). IF it has removable cell caps check specific gravity with a hydrometer. If it is the sealed type do a load test on it. If the battery proves to be good, I would check altenator output, volts and amps. If it is charging properly check for a draw, like a glovebox light or something staying on overnight. Also check for a dirty/ loose neg. battery connection where it grounds to the frame. Check for loose wires at the starter. If all this checks out o.k. and the problem persists I would pull the starter and have it bench tested for voltage drop. The reason I suggested checking all of the above before condeming the starter is that generally, but not always, a bad starter will show up on a warm engine, not a cold one. Hence the old saying '' won't start cold, suspect the battery etc... won't start hot, condem the starter''. Good Luck Dave

Rather than rewrite this one, here's a copy of a little bit of info from my files about alternators that might help your problem and might help others that want to know about the technical marvels that some call "alternators" and that I call &^$$&^*!!:

The first thing to remember is that the auto industry "spared all expense" in making alternators. The second is that you really need an o-scope to see how dirty the alternator output is. The alternator output is a sine wave and then rectified, either half or full wave, then smoothed to some extent to take or minimize the ripple between the peaks of the rectified waves. Most alternators are single wave output. A reason to use 3 phase rectified is to have more peaks and create six sets of rectified peaks reducing ripple even more. The auto battery also acts like a huge capacitor to smooth the ripple and mitigate voltage transients from the alternator so don’t look for a smoothing circuit on cars, normally a bank of capacitors--and now you know why people that install big stereos also install those big capacitors.

So if your alternator output before the rectifier is 30, half of 30 is 15 and with losses and meter issues with ripple, a measured DC voltage at the alternator might be between 14.4 and 14.8 VDC.

What happens with bad or weak batteries is that voltage transients (spikes) get through and damage other circuits. Examples are all the “noise” suppression the auto makers add to keep the static out of the radio and speakers. Remember that most of the “noise” is coming from the alternator. Most of the circuits have some sort of “power cleaner” or filter to help out. This shows up as the voltage level the devices operate at, normally less than 10 VDC, sometimes as low as 3 Volts DC.

So, the alternator voltage out is a reasonable value and the rectifier doesn't help much to clean up a dirty alternator the way they are built. And most auto circuits are pretty well protected from voltage spikes. But remember that current really kills the circuit (lets the black smoke trapped in the wires out--remember, this is really important--you do not want to increase the current in any automobile circuit and that includes spark plug wires by using low resistance wires!!!) NOT voltage. The unrectified AC voltage saturates the circuit and allows to much current to flow which overheats the small components which causes them to fail (read that as a weak battery is really bad for your car and not just becuz it doesn't have the capacity to power things like the starter, but becuz it fails to clean up the dirty alternator output and that can destroy all the little black boxes that are everywhere in the wiring harness and that includes the ignition coil).

About the only thing an owner can do for an alternator is pull the brushes and replace them if they are chipped around the edges (a source of noise). Otherwise we all have to live with what was provided with the car. The other alternative is to replace the diode bridge. If your car continues to lose new batteries or fails to properly charge it, then suspect the diode bridge. The Diode Bridge converts the Alternating Current (AC) into Direct Current (DC), and if just one diode is weak, that means the 3 phase alternator turns into a two phase alternator and that means 1/3 of the voltage getting into the battery is AC. The battery is a huge sump for AC, but too much will overheat and burn it out, and this can happen very quickly. An interesting part of this is that an alternator with a defective diode bridge might test as good with the proper voltage output.

If you need a new alternator and are tired of the rebuilt crap that is usually available, this company sells the only brand new alternators that I know of. Check out the dual diode bridge model--I had that on my car and it helps to make your car's electrical system far more efficient--it also splits the load on the diode bridge:

http://www.alternatorparts.com/Extreme%20D...-144%20type.htm

A quick check that I've found is 100% accurate is to start the engine, let it idle, then tune the FM radio to a very weak FM station. Turn the volume to a reasonable level and then slowly raise the rpms of the engine and then let it return to idle. If you can hear a whine in the FM radio that rises and falls both in loudness and pitch when the rpms are raised, then the diode bridge is a gonner.

Hope this helps

Wow! The above post about the altenator brings back memories about being in auto/diesel tech college 30 odd years ago It all sounds very logical, but don't forget to check the simple things first before condemming the altenator. Dave

Thanks fior all the great info.

Well, I took it back to Sears and they put in a new battery. They don't know why the last one was dead. They said the alternator os okay.
I am watching it now. This one is only putting out 12 amps. My 02 Trans Am's Wal-Mart battery puts out a solid 15 ice cold.

My friend said it does look like the alternator... or maybe an open circuit or bad ground.

I'm not much of a mechanic. Should I just take this thing over to Chevy and get it looked at?

If it turns out to be the alt., what is a reasonable price, considering it's a 15 year old car with 210k?

thanks

What you want to measure is what voltage the battery puts out--not amps. The alternator creates amps--it's rated at 140 amps, but voltage is what is used. The battery should put out around 12.6 to 13.2 volts or about 2.2 Volts per cell and there are six cells. Figure if the battery is only putting out 12 volts, it is pretty much dead already.

If you take the car to GM and tell them to fix it, they will do just that using a rebuilt alternator from whatever supplier they buy from and take your old one as an exchange. They will also charge you about 70-150 dollars to install it. Figure on a bill of about $300 or more. Also, figure that, since it is "rebuilt", it will also probably fail. No one, not even GM will sell you a brand new alternator except for that address that is in my previous posting.

You can buy a brand new alternator from that source that I listed for less than that, buy the tools, install it yourself and it will not fail. Tools that are needed are 5/8 and 1/2 inch box wrenchs, 1/2 inch socket with a breaker bar to release the drive belt tension pulley and a 14 mm or 9/16ths socket for the lower alternator pivot bolt. Release the tension on the tension pulley (under the car) using the 1/2 socket and breaker bar, slip off the belt from under the car. Disconnect the battery negative lead, then unbolt the alternator--two 1/2 inch bolts on the back--one on top and one on the back, remove the 1/2 inch nut that holds the main power lead, and disconnect the exciter connection from the back). Remove the the main pivot bolt from under the alternator using the 9/16 on the front and the rear nut is a 5/8ths (use an open end wrench on both or use a socket with a ratchet on the front. Also, The 1/2 inch bolts on the back are 12 mm sockets and the lower pivot bolt is a 14 mm . It's a very easy job. Takes about 1/2 hour to maybe 1 hour if you've never done it before. The 1/2 inch bolts are the equivalent of 12 mm and the 9/16 bolt is the equivalent of 14 mm.

Also, remember what Blu2000 said: "Check the simple things first". Look for bad connections and a bad starter solenoid.