Odd alternator/choke issue

[mbrew2]

Just recently, the alt warning light has been coming on intermittently. Some times will stay on for couple of minutes, sometimes just kind of flashes on and off. Doesn't happen at start-up, only when driving. Was thinking loose wire somewhere but can't find anything. Could a faulty voltage regulator cause this?  Odd thing is that when this happens, the engine goes into fast idle as if the choke was on and stays that way even after the light goes out. I have installed a Summit brand carb and it has been working perfectly until now. It solved all my hot hard start issues and the choke has worked the way it should. I can pull over and shut it off/restart and everything goes back to normal. Doesn't happen everytime I drive it, just occasionally but has me concerned about putting it on the highway for 50-60 mile runs. Any suggestions? Due to it only happening while driving , I can't check voltage to see if it is just a fault light.

 

[Don C]

Electric choke? And what does it's power come from?

 

[mbrew2]

Electric choke? And what does it's power come from?

Yes, electric choke. I haven't tried to trace the power lead, I used the existing wire that was on the edelbrock that I replaced. It worked perfectly until the alt light issue came up. I suppose the 2 problems could be unrelated but occur within the same time frame. Normally the choke would activate on cold start-up and then go to normal idle with a blip of the throttle but now when this happens it won't throttle down unless I turn it off.

 

[Don C]

The possible connection is that the original way Ford connected electric chokes was to the stator terminal on the alternator.

The next time it happens I would pull the lid off the air cleaner and see if the choke is partially closed, if so that is why the idle speed increases.

The stator receives voltage from two sources, when the engine isn't running it receives battery voltage to energize it when the key is turned on, through the alternator warning light, which is why it is on before starting the engine. After the engine is running the stator voltage is supplied by the field coils in the alternator, removing the load through the alternator warning light and turning it off. So, because your warning light goes on and off the stator is likely not getting power, which in turn doesn't heat the winding in the choke, allowing it to cool, and closing the choke.

The problem may be the regulator, but I suspect it's the alternator. AutoZone, and other parts stores, will test it for you, if you don't have a voltmeter and ammeter.