Choke not pulling off
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Elder User
Joined: Jul 2008
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Choke not pulling off
I removed the reman. carb that was on my 302 and replaced it with a rebuilt carb. off my 77 T-Bird that had a 400 and runs great but the choke is staying on forever and can't seem to get it to come off.... The choke is part electric part manifold heated meaning there is a tube that comes from the exhaust manifold to the choke housing. There is also a 12 volt source that plugs into the choke so I really not for sure what the problem could be?? Any thoughts? I don't know where to even adjust it??
Lead Driver
Joined: Feb 2003
Posts: 8,140
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From: Oak Harbor, OH
Test the wire going to the choke. Make sure it's got 12v. From there is the choke moving? What carb is it, and how is the choke set up? The carb on the 460 in my '77 is a bear, the choke pull-off is internal and all the linkages stick. It's a beast to start when cold if you forget to set the choke before you get in it. Is there a vacuum pull off that's not operating correctly?
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Elder User
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The choke will come off I just have to keep tapping the throttle until it does. Haven't checked for 12V yet but I will. It has a external choke pulloff and I believe the carb is a 2150?? Sound right?
Lead Driver
Joined: Feb 2003
Posts: 8,140
Likes: 4
From: Oak Harbor, OH
2150 2bbl. Yup, check and make sure the choke housing where the choke stove attaches isn't broken. I had one a '79 LTD break and then the choke didn't pull off ever. If that checks out then you might want to adjust the choke pull off. On the back side of the vacuum pull off there is a round access hole. There is a 1/4 bolt there that you use to adjust the pull off. It should pull off just enough the let the engine run until the electric/choke stove has heated up enough to pull it off the rest of the way.
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Elder User
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Oh interesting I wondered why there were both... Well when you first start it cold it runs on fast idle then you tap the accelerator and the fast idle comes off. But the wierd part is while waiting for the choke to completely come off it goes back into fast idle then it takes forever for that to come off but it will eventually. Does that make any sense??
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Lead Driver
Joined: Feb 2003
Posts: 8,140
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From: Oak Harbor, OH
Yes, that's normal. Until the choke pulls off it should run on fast idle. It sounds like the vacuum pull-off is not working to me. You need to have a helper start the car while you have the air cleaner assembly off. Watch the choke plates, if they move after the truck starts then the pull-off is working and needs adjusted. If they don't move at all the pull-off is not working, make sure there is vacuum to the line on it, and from there replace if needed.
MSEE
Joined: Apr 2004
Posts: 10,386
Likes: 35
From: Austin, TX
If you use your DC meter to check the choke voltage, you're only going to see 6-7 V RMS. This is because the stator signal is actually AC, so don't be alarmed if you don't see 12V DC. Take a look inside your choke cap and make sure the spring is intact. It grounds by the tang slipping into the choke linkage itself. Here's my writeup on pretty much everything you need to know about setting up the choke and fast idle on a 2-barrel carburetor. There is a part about indexing the choke cap properly. Ignore the first couple paragraphs about the float.
https://www.ford-trucks.com/forums/7...ml#post6422219
https://www.ford-trucks.com/forums/7...ml#post6422219
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Elder User
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If you use your DC meter to check the choke voltage, you're only going to see 6-7 V RMS. This is because the stator signal is actually AC, so don't be alarmed if you don't see 12V DC. Take a look inside your choke cap and make sure the spring is intact. It grounds by the tang slipping into the choke linkage itself. Here's my writeup on pretty much everything you need to know about setting up the choke and fast idle on a 2-barrel carburetor. There is a part about indexing the choke cap properly. Ignore the first couple paragraphs about the float.
https://www.ford-trucks.com/forums/7...ml#post6422219
https://www.ford-trucks.com/forums/7...ml#post6422219
Ford Parts Specialist
Joined: Nov 2006
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From: Simi Valley, CA
DOAZ9J549C .. Choke Pull Off Diaphram (Motorcraft CK1283).
This diaphram doesn't usually come with carb kits, must be bought by itself.
Fits: 1970/79 Ford 2V carbs except 1977/79 VV's.
Mounts under a cover on the airhorn that uses three screws to retain it.
All you see is the diaphram's 90 degree rod poking out of the cover.
Careful when removing the diaphram, there's a coil spring beneath it.
This diaphram doesn't usually come with carb kits, must be bought by itself.
Fits: 1970/79 Ford 2V carbs except 1977/79 VV's.
Mounts under a cover on the airhorn that uses three screws to retain it.
All you see is the diaphram's 90 degree rod poking out of the cover.
Careful when removing the diaphram, there's a coil spring beneath it.
MSEE
Joined: Apr 2004
Posts: 10,386
Likes: 35
From: Austin, TX
You should check the voltage when it first starts, and then check it again after it runs for a few minutes to see if it changes. The reason for this is because the electric heating element in the choke is a positive temperature coefficient (PTC) heating element - meaning that it presents a very low resistance and draws a lot of current at first which will make the voltage read very close to zero. As the element heats up, its resistance increases until it approaches open-circuit, at which point the voltage will return to 6-7 V RMS. If the choke power reads 6-7 V RMS when disconnected (normal) but stays at zero after you connect it and leave it running for a few minutes, then it's possible that your choke cap is bad. In that case it might be shorting to ground.
The stuff to pay attention to in the article is the choke cap index part because it shows you how to adjust how long it takes the choke to open up. If you're not having any problems with the idle kicking down then you can probably skip over the fast idle stuff, but if your choke never opens then I'd imagine your idle never kicks down, so you won't know if that's good until you get your choke to open.
The stuff to pay attention to in the article is the choke cap index part because it shows you how to adjust how long it takes the choke to open up. If you're not having any problems with the idle kicking down then you can probably skip over the fast idle stuff, but if your choke never opens then I'd imagine your idle never kicks down, so you won't know if that's good until you get your choke to open.