I was driving the other day to work at 4am and since the outside temp was in the 50's I had the heater on coming out of the front vents. I suddenly started smelling the burning metal smell. Then I noticed the choke light was on and also the voltage had gone down from the normal 12.5-13 to slightly lower than 12V, even after I turned off the heater blower. Also, the engine RPM would not go lower than the high idle RPM (about 1100-1200RPM).

Troubleshooting done:
-Checked voltage at Choke Thermostat wire and it was normal around 12V (with engine off or running)
-Checked voltage at battery with engine off and it was about 12.5V.
-Checked voltage at battery with engine running and voltage was around 13.1V
-When I disconnected the choke thermostat wire, the choke light turned off.
-Guy at Kragen checked voltages with some fancy looking multimeter and said alternator was bad because the voltage was not increasing enough when the engine was turned on.
-Checked resistance of choke thermostat (once it was hot I think) and it was around 35 ohms.

I drove to my parents house 40 miles away and the voltage (according to the dash gauge which seems to be consistent) started out about 12V and it hit 11V as soon as I got to my parents house and the choke relay started buzzing.

I did not notice the headlights dimming or flickering on my way to my parents house.

Surprisingly, the car started today and the battery voltage was around 12.4V with engine off and about 13.1V with engine on.

I already bought an Autolite Pro alternator with lifetime warranty at kragen for $83 (price match to Partsamerica.com from $105 to $100, -25% off coupon ) but have not installed it. I am going to remove the old alternator and get it tested outside of the car tomorrow.

With the symptoms I described, what do you think the problem is? The alternator? Is the voltage at the battery supposed to be ~14V with engine on?

 

can't confirm or disprove more than what you've been told personally, but yes it does sound like your alternator is bad, and you should be roughly floating at 14ish, much higher than that and you should worry about over charge to your electronics...some car electronic devices actually tell you that they conform to voltages between 10-14V, which shows the variance between using other electrical devices in the car and other things that may drain the battery, but every device i've seen recommends ~14V to operate optimally, and thats what your alternator should be putting your battery up to. I would say change the alternator and trouble shoot from there, otherwise it's just a shot in the dark trying to guess what could be wrong without really trying anything. Good luck!

 

Yup, it turned out to be the alternator. Ever since I got my car, the voltage has always been at 13V at idle with everything off and never had any problems until now. I installed the new alternator and the voltage is now at 14V.

My car is still idling kind of high around 800RPM vs the old regular 500-600RPM. Could my choke thermostat have been damaged when the alternator burned up?

 

that i would assume is the voltage spike...possibly was timed/set for the lower voltage and now it's getting 14V it's different? Can't really comment on that or the choke thermostat, just hypothesize. Good luck and happy to hear the alternator worked out.

 

You'll have to remove the air cleaner and inspect that the choke opens fully and that the fast idle cam isn't stuck. You can reach it between the carb & the choke heater housing, and push it down. Give it a shot with some lube if it sticks. It's most likely a coincidence.
Btw., the choke shouldn't get any voltage until the car runs.

 

I'll check if the fast idle cam sticks tomorrow morning. You are probably right about the voltage at the choke wire. I'll double check that too. Thanks for your replies.

 

It could be idling higher just because the ignition now has more voltage at idle. I know my car will idle down a bit when the alternator charging wire is disconnected.

 

It is idling around 900-1k RPM when in Park, but when In Drive and stopped, it idles around 500-600RPM. It used to idle around 650 RPM in Park before, and 500RPM in Drive.