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The alternator checks out...

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DesertSprite

Jedi Warrior
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Well, it isn't the alternator. Just had it tested Saturday afternoon and it checked out fine. So...maybe its the voltage regulator?

The shop that tested the alternator for me told me to hook everything back up, charge up the battery, then hookup a test light to the battery and start popping fuses off. When the light goes out, that's where the short is. The guy was fairly certain that I have a short in my system somewhere that is draining the battery.

But...that doesn't explain the weird behavior just before it cut out. I think it's probably a short AND something with the distributor.



Joel
 
Joel,
Your car does not have a "voltage regulator" as a seperate unit, it is built into the alternator. There is a "voltage stablizer" in the ignition circuit that "regulates" the voltage to the instruments. If the current drops below 12 volts to the point you cannot start the car it will also effect the instruments. Check for shorts and get a good repair manual with a diagram of the wiring circuit in it.
 
I have been following this thread for a while, and I can't remember—have you replaced the coil and ballast resistor recently? In my recent experience I have learned that a bad coil or ballast can be the source of all kinds of befuddling problems.
 
The test light might not show much unless you have a significant amount of current draining the battery. You might try that first, but if the test light doesn't glow you might try an ammeter in series with the battery lead instead. Just don't try to start it with the ammeter in series! Does the ignition warning light turn on when you turn the key on? If the light burned out the alternator might not be able to regulate properly.
 
I haven't replaced the coil yet, and I know I haven't replaced the ballast resistor...because I'm not sure what it is. I guess I'm trying to figure out the least expensive things to replace first before I start draining my wallet.

The ignition light does come on. Albeit fainter than usual. I don't get any juice to the fuel pump because I can't hear it when the ignition is turned on.

As for the voltage regulator, I thought that having an alternator meant I didn't have a voltage regulator, but the previous owner insisted his Dad had wired it so that the car retained the voltage regulator along with the alternator. I thought that was kind of odd. He did give me a bunch of wiring schematics that his father had drawn up when he re-wired a few things. For me, wire schematics = headache.

Hopefully he meant to say voltage stabilizer as this makes a lot more sense. However, it was only the tachometer that went berserk. All the other gauges were fine.

This is a frustratingly slow problem to fix. I only have time on the weekends to meddle with the Sprite, and I'm cautiously putting together a parts order before tax time. /ubbthreads/images/graemlins/hammer.gif

Thank God for beer. /ubbthreads/images/graemlins/cheers.gif
 
No. Some people do leave the voltage regulator in when converting to an alternator But basicly gut the regulator so that it does not function, i.e., the current from the alternator just goes straight through as if it wasn't there.
The only way you will find the problem is by chasing the wiring. Better get used to having a headache.
 
I recently replace my coil and ballast resistor for about 16 bucks with over the counter parts from O'Reilly autoparts. If you are interesed, I will post the part numbers for you when I get home. I believe a wigged out coil could cause your tach to freak. Also, typically with an alternator there is a thick red wire that bolts directly to the main relay. That is how it is set-up on my 1500. I would chase the thickest wire coming out of the back of your alternator and make sure it is bolted directly into the main relay. If the alternator is running through an unneccessary voltage regulator, that could definitely be causing your charging system to freak. Also, make sure that the terminal on the main relay is shiny and clean. Corrosion could be causing a poor connection.

morris
 
Well, looks like I'll be following wires this weekend.

Should I just take out the voltage regulator altogether?

Morris, that'd be great to know which part to order. Is it the same on a 1275 as it is for a 1500?

Joel
 
Well, I cracked open the Haynes manual, and if you are running a stock ignition, I don't think the coil I used for my car will work for your car. Sorry. I think it would be possible for you to find a generic coil that will work for your car, but it would require a very knowledgable, helpful, and patient parts counter clerk. I have never met one of those personally.

One test you may try is this: loosen your positve battery terminal, then fire up the car. Once the car is running, remove the cable from the positive battery cable. If the car dies, and you know the alternator checks out, it means that a problem lies between the battery and the alternator. This narrows things down a bit.

Yours is a MKIII Sprite, correct? I have never worked on one of these, so I can only give you generic auto trouble shooting advice. Hopefully someone more knowledgeable than I will come to your aid.

One thing I can say is that having a good digital multi-meter goes a long way to make trouble shooting electrical problems easier. I have a Fluke brand multi-meter that I picked up at a pawn shop many years ago. I love it dearly. Another thing that helps a lot is a pack of insulated aligator clip leads from Radio shack. They will allow you to clip your negative probe to the frame leaving both hands free to chase wires with the positive probe.

If you do have a multitester, one thing that you can do to test your coil is to check the resistance (ohms) across the positive and negative terminals on your coil. According to the Haynes manual, the resistance for your car's stock ignition coil should be 3.2 to 3.4 ohms.

Finally, way off topic, my cousin and her husband are army linguists. She is a Korean linguist (ret.) and he is an active duty Russian linguist stationed in Iraq. (don't ask me)

Also, I have been to China, and it is wonderful. I can't wait to go back.

**in my original post I inserted the symbol for ohms, an omicron, but it came through as a question mark. Therefore I replaced the omicrons with "ohms."
 
Morris may be on the right track here. I had iginition problems some time ago and it turned out to be related to the ballast resistor. As in I didn't have one. If you don't have a proper ballast resistor installed then, in my case, after about 30 minutes of driving, sometimes less, the coil and points would get so hot they would stop working for about 10 minutes and then after everything cooled down, the car would start back up and be good to go again, for a little while. It took me a very long time to figure this out because I never new what a ballast resistor did. I replaced every thing on the car trying to find the problem, including new points, new coils, etc. When I finally figure it out (or had it figured out for me) I had taken my coil in to a local auto parts store to be checked. It checked out OK but was really hot and the guy at the counter asked me about what ballast resistor was I using. He then looked up in his book, pulled a part off the shelf (standard coil with internal resistor) and away I went and I haven't had that problem ever since.

JACK
 
[ QUOTE ]

One test you may try is this: loosen your positve battery terminal, then fire up the car. Once the car is running, remove the cable from the positive battery cable.

[/ QUOTE ]

You should NEVER remove the battery cable while the engine is running!! The alternator depends on having the battery to keep the output loaded, and without the battery in place the alternator output can be way over 12 volts, usually frying the zener diode, regulator, and anything in your electrical system that doesn't like high voltages (like light bulbs, ignition systems, radios, etc. I'm pretty sure I even have a warning label under the hood of my Midget that says not to do that. This is pretty much true for any alternator. A friend with a motorcycle tried that and I think after he replaced several indicator lights, the ignition coil, and the bike's voltage regulator, he made sure never to do that again.

-Dave
 
I did not know that. I have always used that test to determine if alternator current is reaching the battery and never had a problem.

Oh well, I guess you learn something new every day.

Sorry for the bad advice Joel and thanks for the save Dave.
 
Huh...do the coils from Moss, such as the OEM replacement or Lucas Sports ones have ballast resistors? I think I read that the Crane Cams or Pertronix ones have them. I remember there being a stipulation about being used with ballasted or non-ballasted ignition systems.

I do not have a multitester, however, that seems to be headed onto the shopping list as well. What do you guys think of the Craftsman equipment that Sears sells? I've only bought a test light and timing light from them in the past.

Thanks again.

Joel
 
Radio shack shells a nice $15-20 multimeter that I think is of good quality considering the bargain price. Multimeters have a sky-high upper price range, but even the cheapies aren't too bad. Mostly it's a function of the simlicity of it (fewer doodads).
 
I just looked at the Crane Cams coil and it says it has a ballast resistor inlcuded in the coil. Would I still be able to run an electronic ignition inside the distributor with a ballast resistor?

Matthew, thanks for the info. That's my kind of price.

Joel

/ubbthreads/images/graemlins/patriot.gif
 
The saving grace as far as unhooking the battery on the Midget could be that since the alternator isn't very powerful, running the ignition and whatever accessories may have been enough to keep the alternator from getting too carried away, but still not a good idea. Basically the residual magnetism in the field is enough to generate some power, so there is a minimum output it will generate which usually needs the battery to absorb some of it.

Joel, as far as multitesters go... Radio Shack isn't bad, but you might look for one that has a 10 amp current range or more, since that's handy for car electronics. Fluke would be the best, but they tend to be on the expensive side. Sears carried some Flukes at one time. Don't know too much about Craftsman, but nowadays even the cheap meters are pretty accurate and even have things like temperature and capacitance. I happen to like the Fluke because it's very accurate, it has no mechanical adjustments, and it's pretty rugged both electrically and mechanically.
-Dave
 
What ignition are you running on the car? If you are running an after market ignition, the manual should give you an idea of what you should get. My Lumenition system does not like low resistance high output coils. The manual says the minimum resistance I should run is 1 ohm and the total resistance for coil ballast combinations should be at least 3 ohms.

If you are running stock ignition, I think the stock coil is internally ballasted. This is my guess based on a quick look at the Haynes manual. If it is okay to run an externally ballasted coil on a stock set up (someone more knowledgable please chime in) then you can probably get away with using the set up that I have.

The O'Reilly's part number for the coil is E31. It should be about $10. The primary resitance on the coil is 1.5 ohms. The part number for the ballast resistor I have is either R4 or RU4. It's resitance is 1.5 ohms as well. I don't reccomend this resistor as it is difficult to mount in the car. See if they will dig around for another resistor that has a flat metal mounting tab and a resistance of 1.5-2 ohms. You will have to bring a multitester with you to check the resistance at the parts at the store. The clerk will have no idea.

If you go this route, you will have to make a lead that goes from the ballast resistor to the the positive terminal of your coil. The wire that formally plugged into the positive terminal on your coil plugs into the other side of the resistor.

Again, please check with someone more knowledgable than I before going this route.
 
Fluke meters are reputed to be some of the best ones, but I don't see the need for this application (the beginner automotive restorer).
 
I've got both a Fluke 87V and a craftsman digital multimeter. I have really found no difference (except the price) between them if you aren't worried about which category the meter happens to carry. Basically the category has to do with how much fault current the meter can stand without disentegrating in your hand and blasting copper bits all over you (talking about way higher voltages than what you would see on a car). The fluke is great for industrial work and the craftsman is good for automobile maintenance. Just my $.02. Save the money for more goodies for you car if you don't plan to ever be an industrial electrician.
JC
 
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