Another question. Choke Hot Wire?
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Freshman User
Joined: Nov 2012
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Another question. Choke Hot Wire?
Alright, I'm having a cold start issue. I got under the hood to adjust the choke today. With a test light, I found that the wire going to the choke was hot only while the truck is actually running, and not when key is just turned on.
I figured that this defeats the purpose of having a choke if it doesn't work until the truck is running. I went ahead and ran a new wire to the choke that is live when the key is turned on. I then adjusted the choke. Guess we'll see if it starts without fluid in the AM.
So, did someone screw up with the choke prior to me? Or did I mess up by changing it?
I figured that this defeats the purpose of having a choke if it doesn't work until the truck is running. I went ahead and ran a new wire to the choke that is live when the key is turned on. I then adjusted the choke. Guess we'll see if it starts without fluid in the AM.
So, did someone screw up with the choke prior to me? Or did I mess up by changing it?
Posting Guru
Joined: Oct 2010
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From: Missouri
You hit the gas pedal to set the choke when cold, power is only used to disengage the choke.
You don't want the choke opening up if the engine is not warming up (running). The setup you have was most likely getting power from the altenator.
You don't want the choke opening up if the engine is not warming up (running). The setup you have was most likely getting power from the altenator.
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Thank you.
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Alright, now that I know how it works, I think I have the problem solved. When hitting the pedal, the choke was closing all the way. I just adjusted it so a little air is still going in with it closed. Seems to have solved the problem.
Posting Guru
Joined: Oct 2010
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From: Missouri
Good job.
If I remember correctly the choke does close all the way when you hit the gas, then when the engine actually starts it is supposed to crack open some. One version uses a rubber diaphragm and another uses a little piston that is visible if you remove the choke cap. Whichever system you have, if doesn't crack the choke open correctly after starting the engine.. it would likely go too rich and die.
Here is a random youtube video that shows the action of the choke, start watching at the 1:00 mark to see them start the engine and the choke cracking open correctly. If yours is functioning similarily then you should be good to go now.
If I remember correctly the choke does close all the way when you hit the gas, then when the engine actually starts it is supposed to crack open some. One version uses a rubber diaphragm and another uses a little piston that is visible if you remove the choke cap. Whichever system you have, if doesn't crack the choke open correctly after starting the engine.. it would likely go too rich and die.
Here is a random youtube video that shows the action of the choke, start watching at the 1:00 mark to see them start the engine and the choke cracking open correctly. If yours is functioning similarily then you should be good to go now.
Elder User
Joined: Jun 2010
Posts: 509
Likes: 4
From: Casper, Wyoming
You need to put it back as before. The choke is connected to the field wire of the alternator, which produces around 7 volts, matching the requirements of the choke. FoMoCo did this so that the choke heater heats only when the engine is running, not as soon as the key is in the on position. If you've wired it to 12V, the choke will fail sometime this winter and you'll be unhappy.
Alright, I'm having a cold start issue. I got under the hood to adjust the choke today. With a test light, I found that the wire going to the choke was hot only while the truck is actually running, and not when key is just turned on.
I figured that this defeats the purpose of having a choke if it doesn't work until the truck is running. I went ahead and ran a new wire to the choke that is live when the key is turned on. I then adjusted the choke. Guess we'll see if it starts without fluid in the AM.
So, did someone screw up with the choke prior to me? Or did I mess up by changing it?
I figured that this defeats the purpose of having a choke if it doesn't work until the truck is running. I went ahead and ran a new wire to the choke that is live when the key is turned on. I then adjusted the choke. Guess we'll see if it starts without fluid in the AM.
So, did someone screw up with the choke prior to me? Or did I mess up by changing it?
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Junior User
Joined: Nov 2012
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From: ok
your choke closes to between 3 and 7/32.you should be at around the rich mark right now,there is a high idle cam adjustment passenger side(high idle 2000 rpm-1800 rpm).and the reason the choke pot is only recieving power when running is it should be wired to the field wire of your alt..it takes trial and error,and a real cold night,but with 1 full pump,the choke should fire your engine,run it at 1200,up to 1600 and then 2000,then idle(fast idle cam usually gets a lil wear and sticks at 2000 and needs a throttle tap).if you stick at high idle,a little polishing of the cam and some lube will solve it.point is,you should be able to pump once,hit the key and run for the front door even in the coldest of weather.
(hint to adjusting choke pot.with engine cold,and weather cold turn to rich until the choke just closes,then a shade more.)cycle the system.if it works,pop the hood let it cool a full 2 hrs then do it again to verify operation.
(hint to adjusting choke pot.with engine cold,and weather cold turn to rich until the choke just closes,then a shade more.)cycle the system.if it works,pop the hood let it cool a full 2 hrs then do it again to verify operation.
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From: Virginia
It will take a few mornings to figure it out, and a few more to get it adjusted right. If you are trying to get the choke "just right" so it will not close all the way and flood out, you will never get it. The previous poster was correct, the choke closes all the way when you first hit the gas on a cold engine, and then some sort of mechanism(different carbs use different methods) cracks open the choke just a little bit when the engine starts. This is called a "choke qualifier" or a "choke pull-off". This thing can also be adjusted, it can crack the choke door open too much and stall the engine.
Elder User
Joined: Jun 2010
Posts: 509
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From: Casper, Wyoming
If it starts, leave it alone. If it floods, , repeat the process, turning the choke towards the "lean" side.
It usually takes me a couple days to get it dialed in, but once it is, it's perfect.
To check the choke pull off (I've always referred to it as a choke unloader, thanks to Franklin for using the correct term), set the choke as described above, then open the throttle all the way: the pull off should open the choke a small amount. If it doesn't, ask the guy behind the parts counter to let you look at the instructions in a carb kit for your engine for the proper procedure. Some have an adjustment, others require you to bend a link, etc. You might even find it on Google if you know which carb you have.
Happy wrenching!
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