Car won't run with alternator on

[DJCarbine]

I have a seperate switch that turns on the coil, and the alternator is engauged by the key turned to the run position. This means I can start my car, and actually turn the key off and remove it and it will still run untill I kill the coil power. This was temporary untill i finished wiring my ignition system.

Due to a starting issue, I reverted from my pertronix unit back to trustly old points. Car starts great now and runs, granted its -5 outside it still starts up and idles decent untill it warms up, where it idles great.

However, recently I have only been able to get it started and idling with the key removed, which means the alternator isn't charging. As soon as I turn the key to have the alternator charge, the rpm's drop immediatly and the engine more or less dies within seconds. The interior lights to brighten up, and the volt meter hits 14, which means its working more or less correctly, but the engine dies. It sounds like its not getting ignition. Even with the throttle down, holding it at around 2.5k rpm, turning the alternator on will result in severe misfires and the engine dying untill I remove the key, where it runs normally.

I checked the battery to engine ground, and it seems good. There is a ground coming off the alternator that appears to be the original wire, with electrical tape holding it together

I plan on redoing the wiring to the alternator, but have come here for advice. It is about a -35 windchill outside right now, so its too cold to start working on it. Would this crappy old brittle alternator wiring be causing this issue? The coil is getting 12v straight from the battery, the points are adjusted right, and the car otherwise starts/idles great. Once last night after it fully warmed up I was able to engauge the alternator and it was OK. I tried it later and it died.

Have I found the problem? Does it make sense?

 

[Rusty67]

If you know you have a dodgy ground then the first thing I would do is fix it. If that isn't the cause then I would guess you have a bare or crossed wire issue AFTER the ignition switch in some of the wires.

Powered by Profanity ? I'm not the only one !

 

[CraigMBA]

If you think you have a problem with a ground wire, you can temporarily improvise one with a set of jumper cables. Remember there are two ground wires - one from the chassis to the block, and one from the block to the battery.

If you gas it when the alternator is running, does it die then also? Or only at idle?

 

[DJCarbine]

If you think you have a problem with a ground wire, you can temporarily improvise one with a set of jumper cables. Remember there are two ground wires - one from the chassis to the block, and one from the block to the battery.

If you gas it when the alternator is running, does it die then also? Or only at idle?

If I give it gas and try to feather it, it will still die. Its like its losing ignition completely almost. I will miss and pop and then die. I could rev it to 4k and turn the key to on, and it would die. I am going to redo the alternator wiring tomorrow when its not so damn cold outside

 

[DJCarbine]

redid wiring with new wire, checked the voltage regulator connections, started the car... and it dies. Disconnected alternator, car fires right up and idles fine

Wiring is good, battery is good, engine mechanically fine, spark fine.......

Possible bad alternator?

Did I wire my points up wrong?

I don't see how, as its 1 wire......

Battery to engine ground is clean and fine. That ground is then connected to othe ground post on the alternator leaving 2 other posts, white and red which are in turn connected to their respective wires. Red getting power all the time, and white going god knows where, possibly the voltage regulator.

Coil gets 12v from a relay under the hood, and points are connected to the - terminal on the coil.

On a side note, I can start the car and then connect the alternator, and it will begin to idle slower and sound worse, and I won't be able to rev the car up at all without it trying to die.





Suggestions are welcome, I am at wits end. I also ran a new ground wire from the head to the firewall, the manifold ground didn't exactly look.... sufficient.

 

[ForceFed70]

To me, it sounds like your wiring is starving the ignition coil of voltage. Resulting in a very weak start.

Start up the car with the alternator off and measure the voltage at the + terminal of the ignition coil. Then turn on your alternator and see if the voltage drops.

I'd expect to see approx 9V at the coil if you are using a ballast resistor, 12V if you arn't.

Try that test and we can go from there.

 

[DJCarbine]

12 volts at the + terminal of the coil, I haven't been able to get the alternator hooked up and do a test at the coil because its runs so poor and dies quickly.

The voltage gauge in the car shows the system at 11 volts running with just the battery, and jumps up to 14v when the alternator is switched on.

The wiring for the coil is a direct line from the battery to a bosch relay, then to the coil.

I will try to get the alternator switched on and take a voltage reading, its a bit hard because the engine dies so quickly. The lights do get brighter and voltage gauge goes up, so I would hope to assume that a line coming directly off the battery going to the coil would still be at the 12-14 volts that the gauge is reading.


Ill see if I can get a direct reading tomorrow

 

[DJCarbine]

Maybe its just me, but my alternator has 3 posts, and everything in the haynes manual and on schematics on the net have 4 posts/wires coming off the alternator going to the voltage regulator?

Maybe the PO did some funny business?

 

[suki243]

If I remember correctly from my own alternator woes, 1 wire alternators are called one wire cause they only connect to the battery directly in one way or another. But usually they usually have 3 posts connecting to each other or the voltage regulator in some way.

I had the original one in it, and when i disconnected the red battery cable it ran fine, till it came to when i added the new stereo, then it pulled too much from the alternator, and when i disconnected it from the battery it died immediately. I got the alternator tested from Kraigen and they said it was fine. I put in my new 1 wire 120 amp alternator, and disconnected the battery it stays on...

Just my .02

 

[Rusty67]

There is no way for us to know what alternator you have without pictures or at least some part numbers. Please post pics/part numbers if you can.

 

[DJCarbine]

There is no way for us to know what alternator you have without pictures or at least some part numbers. Please post pics/part numbers if you can.

Stock replacement alternator from autozone, its got 3 posts and was virtually identical to the old one I took off. I will take pics today, I have some spare time to work on the car

 

[ForceFed70]

It really does sound like a problem with ignition coil voltage/wiring.

There really isn't any other electrical system that could effect how the engine is running.

Can you get someone to help you? You measure the coil voltage while he/she starts the car and then flips the switch? Voltage at the battery won't tell you much here, you need to measure the voltage directly at the coil.

 

[DJCarbine]

Tested the voltage at the coil with alternator on, jumps up to 14 volts when alternator is switched on. Turn the alt off and it goes back to 11-12 and starts to run great.

Went to autozone and they tested the alternator. Said it was bad, but I have a lifetime warranty on it

Put the new one in and the same thing happens

Its not robbing power from the coil, it does indeed put out the voltage it should, and all the grounds have been doublechecked/taken loose and cleaned.

Coils getting power, the points are adjusted correctly, it just starts to bog down and miss. Before it dies the carb likes to pop a few times to let me know its not happy.

Ignition issue... but.... where......

I might end up getting a ballast resistor and seeing if the points would rather run on the lower voltage they are supposed to get. Maybe the resistor wire/ballast is there for a reason lol

 

[DJCarbine]

Oh and about the wiring on the back of the alt, the only wires that are hooked up at BATT/Field/GND

the STAT post is not hooked up to anything.

 

[DJCarbine]

Points/coil don't like full 12-14v power. Put a resistor wire in and it solved the problem. My guess was arcing through the points when the alternator gave the car full juice.

Put the pertronix back in for ****s and giggles... it starts!
Runs OK, but after about 2 minutes the idle drops considerably and begins to miss. I can rev it up, and it will rev up OK... then die like turning off a switch. Consistant with what is happening to people with a bad module, its lasted me over 3 years so I'm not worried about it being dead.

Ordering a craine XRi unit, and who knows... maybe it will run right

 

[DJCarbine]

Found an MSD 6A box for 50 bucks. Going to use points to trigger the box, and canceled the order on the crane conversion unit for now.

 

[CraigMBA]

I'd call Pertronix and explain your situation.

They are good people and might goodwill you a new one.

 

[DJCarbine]

I plan on doing that, but it would still only be there to trigger the MSD box

I also found out that the used 6A box I got is in fact an older model box converted to a 6T with a pigtail for a soft touch rev limiter controller. Best 50 bucks I ever spent. Going to throw it in tomorrow.