Voltage Changes After Starting
Printed From: CorrectCraftFan.com
Category: General Correct Craft Discussion
Forum Name: General Discussion
Forum Discription: Anything Correct Craft
URL: http://www.CorrectCraftFan.com/forum/forum_posts.asp?TID=1428
Printed Date: December-04-2024 at 9:42pm
Topic: Voltage Changes After Starting
Posted By: Jim_In_Houston
Subject: Voltage Changes After Starting
Date Posted: April-08-2005 at 4:35pm
While looking for a place to connect my electric choke I noticed something I am curious about. Maybe someone can solve the mystery.
I had replaced my ignition coil with a coil that does not require an external ballast resistor, and I removed the resistor. I connected the hot wire that went to the resistor directly to the + terminal on the new coil.
Before I connected my choke to the hot lead on my coil I decided to double check the voltage at the coil. I am alarmed to find out that with the ignition key turned "on" the voltage at the coil (to ground) measures 9 volts. This threw me. (The voltage measured from the hot side of the starter motor relay to ground is 12 volts.) I decided to start the engine and remeasure. With the engine running the voltage at the coil is 12 volts. So, my choke should work properly connected to that point but, this still makes no sense. Something somewhere is dropping 3 volts. It's not what I don't know that bothers me - it's what I don't even suspect that's got me worried. Any ideas?
Also, on a slightly different subject (I hope), my wire colors change when they pass through a large watertight connector at the rear of the engine. In other words, the wire colors that run to various points on my engine do not match the wire colors in the harness that goes to the dash panel. The same colors exist on both sides of the connector, they are just on different pins on either side of the connector. For example: the red wire with a green stripe now runs to the + on my coil. When it passes thru the large watertight connector it becomes yellow and heads off to the dash panel. The yellow wire on the engine side of the connector connects to the voltage regulator - it becomes orange when it passes thru the connector and heads to the dash. Did Correct Craft do this?
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Happy owner of a '66 and a '68 Mustang
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Replies:
Posted By: David F
Date Posted: April-08-2005 at 5:24pm
Jim:
First thing that I suggest is seperate the choke and the coil. In other words, supply the choke with direct (switched) 12V from the battery. It seems like the choke is acting like a resistor (which it is) and dropping the voltage to the coil (if you have them wired in series). If you have them wired in parrallel, then this does not make as much sense. I believe the same article you referenced about the choke having a specific polarity also warns against getting the 12V from the coil. Now, what is strange to me is that once the engine is running, you are getting the full 12V...this could be because the alternator will really supply about 13.5 - 14.5 volts and the choke is dropping it down to 12v.
Do this test: disconnect the "+" choke wire (from the choke) and read the voltage at the "+" coil terminal. Is the voltage 12v with key "on" and higher while the engine is running? If yes, then the choke is pulling the voltage down.
I just re-read your post and I think you might be saying that you had 9v or so at the coil BEFORE you connected the choke. If so, curious indeed and ignore all I just wrote. That is other than not pulling 12v from the coil to power the choke.
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Posted By: kenny g
Date Posted: April-08-2005 at 11:14pm
i'm guessing the rear half of the color code wireing schematic would change according to what engine was installed.ford,chevy ect.while the wireing harness to the dash would remain the same.
are u working on the 1968 with the ford ?
i can look at my 68 mustang if u need a wire color conformation.859-824-1740
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kenny g
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Posted By: Jim_In_Houston
Date Posted: April-09-2005 at 2:32am
Thanks guys. It's very nice of you to offer. Don't go to any trouble on this one - it's not that important - I'm just curious. The engine runs fine and the gauges work fine. I can trace the wiring out to the dash and make a working drawing.
It is my '68 with a Ford 289 (Interceptor). I am curious about the 3 volt drop, without the choke connected, until the engine begins to run. When running the voltage at the coil is 12 volts. It's a mystery to me.
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Happy owner of a '66 and a '68 Mustang
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