Choke problems with carter yfa
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Choke problems with carter yfa
I've got a 1979 ford f150 powered by a 300 inline 6 with a carter yfa on top...
Just reconnected the choke spring yesterday, and trying to figure out whether I have a hot air choke or electronic...
As you can see, there's a wire coming off the choke in one of the pics, but it's a ground... Don't know if this is correct as previous owner was all about "fixing" stuff... dangling plug to left of carb is 12v hot, plug with loop of wire on right is completely unknown, but probably there for a reason.
There is a broken off metal tube on the driver's side of the choke... really hoping this isn't the thermal tube that I'm thinking it might be.
I also got a picture of the lettering on the choke if this helps.
ImageShack: Host and Share your Photos and Videos - 20101030090314springfie.jpg
ImageShack: Host and Share your Photos and Videos - 20101030090216springfie.jpg
http://img638.imageshack.us/i/20101030090231springfie.jpg/
Just reconnected the choke spring yesterday, and trying to figure out whether I have a hot air choke or electronic...
As you can see, there's a wire coming off the choke in one of the pics, but it's a ground... Don't know if this is correct as previous owner was all about "fixing" stuff... dangling plug to left of carb is 12v hot, plug with loop of wire on right is completely unknown, but probably there for a reason.
There is a broken off metal tube on the driver's side of the choke... really hoping this isn't the thermal tube that I'm thinking it might be.
I also got a picture of the lettering on the choke if this helps.
ImageShack: Host and Share your Photos and Videos - 20101030090314springfie.jpg
ImageShack: Host and Share your Photos and Videos - 20101030090216springfie.jpg
http://img638.imageshack.us/i/20101030090231springfie.jpg/
Last edited by Grendelx; Oct 30, 2010 at 11:42 AM. Reason: edited because pics didnt show up, links would be cleaner but I got a phone call....
Cargo Master
Joined: Mar 2008
Posts: 2,564
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From: Washington
It is an electric and hot air stove choke.
For a quick fix, connect the wire on the choke shown in the first picture to the “S” stator terminal on the ALT. Also, plug up the pipe on the bottom of the choke (broken off metal tube on the driver's side of the choke) as it will suck air while it is running. I am not really sure it is worth fixing the hot air part of the system as the electric will still open the choke.
Jim
For a quick fix, connect the wire on the choke shown in the first picture to the “S” stator terminal on the ALT. Also, plug up the pipe on the bottom of the choke (broken off metal tube on the driver's side of the choke) as it will suck air while it is running. I am not really sure it is worth fixing the hot air part of the system as the electric will still open the choke.
Jim
MSEE
Joined: Apr 2004
Posts: 10,386
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From: Austin, TX
The electric assist was originally meant to only help open the choke faster - I don't believe it's meant to be the sole heat source. It's really not too complicated to fix - you can make a new one out of brake line, or you can find a repair kit as parr4 mentioned. I do believe it's a Dorman kit and shouldn't be too hard to find.
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Joined: Dec 2007
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From: Boise, Idaho
That's probably why the stock one required only 7 volts. It was just an assist.
And why aftermarket carbs (such as the Holley 4bbl) require upping the choke wire to a 12v source. They need the extra volts because they're the sole source of opening the choke.
I'd never thought about it before, but what would happen if you replaced the choke housing with the Holley choke thermostat and resourced the choke wire to a 12v source? I know it'll fit since I used some of the parts from my 1bbl choke on my 4bbl choke and they were all the same size. That way, you'd only need the electric choke and not have to worry about re-bending pipe to hook up the hot-air tube.
Holley Performance Products Replacement Electric Choke Cap 45-258
You'd need to ground it.
Thoughts?
And why aftermarket carbs (such as the Holley 4bbl) require upping the choke wire to a 12v source. They need the extra volts because they're the sole source of opening the choke.
I'd never thought about it before, but what would happen if you replaced the choke housing with the Holley choke thermostat and resourced the choke wire to a 12v source? I know it'll fit since I used some of the parts from my 1bbl choke on my 4bbl choke and they were all the same size. That way, you'd only need the electric choke and not have to worry about re-bending pipe to hook up the hot-air tube.
Holley Performance Products Replacement Electric Choke Cap 45-258
You'd need to ground it.
Thoughts?
Cargo Master
Joined: Mar 2008
Posts: 2,564
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From: Washington
I did a “bench check” using a variable power supply to see how long it would take to open the choke with both 7 VDC and 13-14 VDC on a stock YFA. Basically it was about 2 min with 7v and 1 min with 13 volts. In real life the choke plate it trying to suck itself open so this is just a comparison.
It would be simple to just start the truck and watch the choke plate, you would have to bump the throttle every 30 sec or so… all I am really trying to say is it might work OK as is, but this also proves how really cheap I am when it comes to fixing thing that currently work as-is.
I think the point of the 7 VDC stator power source for the choke was it was an easy “power with engine running” source.
Jim
It would be simple to just start the truck and watch the choke plate, you would have to bump the throttle every 30 sec or so… all I am really trying to say is it might work OK as is, but this also proves how really cheap I am when it comes to fixing thing that currently work as-is.
I think the point of the 7 VDC stator power source for the choke was it was an easy “power with engine running” source.
Jim
Moderator
Joined: Dec 2007
Posts: 7,987
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From: Boise, Idaho
Ah, that makes sense. I wasn't sure if the 12v would burn up the coil on one designed for 7v after prolonged exposure.
I know I ran my 1bbl through quite a few ice cold winters without the choke pipe (rusted off), and didn't have many ill-effects.
I know I ran my 1bbl through quite a few ice cold winters without the choke pipe (rusted off), and didn't have many ill-effects.
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Joined: Oct 2010
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From: bristol,pa
I had one of those universal choke tubing kits, I kinda remember it being help brand. Also, when I had headers on my truch, I took soft copper tubing and wrapped it around one of the primary header tubes& plumbed it into the choke. It worked good.
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From: Austin, TX
JimsRebel is 100% correct - the stator signal was used because it is only hot when the engine is actually turning. Thank you for the bench test information - that's very useful. To be honest, though, I'm not sure it's accurate to compare 7 volts DC with 13 volts DC, because when I measured my stator voltage on my '79 at idle with a true RMS meter, it was 2.6 volts RMS. The RMS voltage is the true accurate representation of the DC voltage required to dissipate the same amount of heat as would be dissipated by the AC signal. Let me know if you disagree with my thinking. Reps sent nonetheless.
Cargo Master
Joined: Mar 2008
Posts: 2,564
Likes: 207
From: Washington
Actually - the stock choke doesn't "require" 7 volts DC. The stator signal is the neutral point in a three-phase signal and is quite complex. Your meter simply "sees" 7 volts when you have it set to DC. It's an AC signal, not a resistively dropped down DC signal as would be done for ignition coil power, for example. If you look at it with a true RMS meter, you'll see different results.
JimsRebel is 100% correct - the stator signal was used because it is only hot when the engine is actually turning. Thank you for the bench test information - that's very useful. To be honest, though, I'm not sure it's accurate to compare 7 volts DC with 13 volts DC, because when I measured my stator voltage on my '79 at idle with a true RMS meter, it was 2.6 volts RMS. The RMS voltage is the true accurate representation of the DC voltage required to dissipate the same amount of heat as would be dissipated by the AC signal. Let me know if you disagree with my thinking. Reps sent nonetheless.
JimsRebel is 100% correct - the stator signal was used because it is only hot when the engine is actually turning. Thank you for the bench test information - that's very useful. To be honest, though, I'm not sure it's accurate to compare 7 volts DC with 13 volts DC, because when I measured my stator voltage on my '79 at idle with a true RMS meter, it was 2.6 volts RMS. The RMS voltage is the true accurate representation of the DC voltage required to dissipate the same amount of heat as would be dissipated by the AC signal. Let me know if you disagree with my thinking. Reps sent nonetheless.
<O
</OFor those that like the technical stuff … read on
<O
</OThere are a lot of bad ALT schematics floating around on the web; some are often posted/linked posted on this site. Here is an example of a bad one.
<O
</Ohttp://fordfuelinjection.com/public/alternator/1G-ALT_wiring.gif
<O
</OA 1G ALT only has 6 diodes, the center of the stator Y is just a common metal crimp connections, there are only 3 stator wires which feed the full wave bridge rectifier and the stator output terminal is connected to the outside of the Y not the center of the Y as shown in the above link.
<O
</OThe stator output bypass its positive diode but still needs to use the one of the other 2 negative diodes to complete the return path which means one diode is will be in the AC circuit which will produce a wave form the same as a half wave rectifier.
<O
</OThis link has a correct schematic correct for a 3G
http://fordfuelinjection.com/public/alternator/3G-ALT_wiring2.gif
The 3G Alternator use 8 diodes and has dual Y windings with the windings in parallel to increase current output. The extra 2 diodes are used at the center of the Y are said to increase power output by 10%... but I really don’t understand how that all works.
<O
</OHope this helps, normal I don’t post much technical stuff, usually more like…. If the light glows, it is working….
Jim
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Fixing that line is important. It is part of the feed coming from your exhaust manifold. With that fixed, the choke will work without the electric connector anyways. It was originally designed to assist the thermatic choke already in there. Fix that line and you shouldn't have to big of a problem with your choke working, electrical connector or not.
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Alright... chokes staying disconnected for now, trying to hold off on spending money on the truck till I can start my build... shouldn't be more than a month or 2.
Great info, but my meter reads that wire as a constant ground.... wtf?
Great info, but my meter reads that wire as a constant ground.... wtf?
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