2 barrel carb problem
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Freshman User
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2 barrel carb problem
I just got through rebuilding the carb on my truck (66 f100 with a 352) and I am still having one of the problems I had before the rebuild. It starts and runs great but when you press the pedal it stalls like it won't take the gas. If you pedal it a little and kinda feather the gas it will take it and rev up but once it idles back down it has the same problem. Any ideas? Thanks guys.
Ford Parts Specialist
Joined: Nov 2006
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From: Simi Valley, CA
I just got through rebuilding the carb on my truck (66 f100 with a 352) and I am still having one of the problems I had before the rebuild. It starts and runs great but when you press the pedal it stalls like it won't take the gas. If you pedal it a little and kinda feather the gas it will take it and rev up but once it idles back down it has the same problem.
Bogging down, stumbling, hesitating from a dead stop or when accelerating at speed: Defective accelerator pump diaphram and check valve.
Yes, you rebuilt the carb, and you prolly replaced the diaphram, but what about the check valve?
The check valve fits behind the diaphram, has a tiny nipple on one side that fits into a hole in the carb body. This nipple is notorious for snapping off...and because of this, you have to be very careful when installing it.
You replaced both parts, but while they were new...how old were they?
Ozone, humidity in the air causes these parts to harden up...even when in a box, so depending on how long the parts sat on a shelf, one or both could be defective.
Behind the cover on the front of the carb, between it and the diaphram...is a coil spring.
Is it still there? People are unware of this spring...remove the cover without paying attention, which causes the coil spring to fly out.
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Freshman User
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you prolly replaced the diaphram, but what about the check valve
how old were they
Behind the cover on the front of the carb, between it and the diaphram...is a coil spring.
Is it still there
Is it still there
Ford Parts Specialist
Joined: Nov 2006
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From: Simi Valley, CA
The diaphram is the same 1962/74 (C4AZ9B559A-Motorcraft CM463). 1975/79 is different. The check valve is the same 1962/79 (C4AZ9576A-Motorcraft CM825).
The same carb kit fits all 1962/74 Passenger Cars, F100/350's, Bronco's & Econoline 2V Auto-Lite/Motorcraft carbs (D4AZ9A586A-Motorcraft CT499D).
1975/79, there's a gazillion different kits.
Postmaster
Joined: Mar 2004
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From: seattle
When I did mine the diaphram had a long pigtail that you could grab with a pair of needlenose pliers and pull through until its seated. Then you just snip the end of the tail off and its done...Also I THINK the diaphrams only go in properly one way...Also, the diaphram cover has the arm with 2 holes in it...make sure the activating rod is in the INSIDE hole.
What brand of kit did you get ??? The Motorcraft kit is still available from Ford last I checked...CT499D p/n D4AZ9A586A
- cs65
What brand of kit did you get ??? The Motorcraft kit is still available from Ford last I checked...CT499D p/n D4AZ9A586A
- cs65
Ford Parts Specialist
Joined: Nov 2006
Posts: 88,826
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From: Simi Valley, CA
When I did mine the diaphram had a long pigtail 
that you could grab with a pair of needlenose pliers and pull through until its seated.
You are describing the check valve, not the diaphram.
Then you just snip the end of the tail off and its done.
Take care when doing this...you pinch that pigtail too hard, the tit snaps off. Then you gotta make a RT to the parts store to get another.
Also I THINK the diaphrams only go in properly one way...Also, the diaphram cover has the arm with 2 holes in it...make sure the activating rod is in the INSIDE hole.
What brand of kit did you get ??? The Motorcraft kit is still available from Ford...
D4AZ9A586A (Motorcraft CT499D)
that you could grab with a pair of needlenose pliers and pull through until its seated. You are describing the check valve, not the diaphram.
Then you just snip the end of the tail off and its done.
Take care when doing this...you pinch that pigtail too hard, the tit snaps off. Then you gotta make a RT to the parts store to get another.
Also I THINK the diaphrams only go in properly one way...Also, the diaphram cover has the arm with 2 holes in it...make sure the activating rod is in the INSIDE hole.
What brand of kit did you get ??? The Motorcraft kit is still available from Ford...
D4AZ9A586A (Motorcraft CT499D)
Parts Guy Ed = Ed Olson, parts manager of Horizon Ford in Seattle (Tukwila) WA
The diaphram has a circular piece of metal in its center. It only fits in one way, because the coil spring butts up against it.
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Postmaster
Joined: Mar 2004
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From: seattle
Thanks for the correction Bill...The price amazes me...alot cheaper then when I did mine.
- cs65
- cs65
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Postmaster
Joined: Mar 2004
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From: seattle
Be careful here also as theres a couple of check ***** as I recall...One problem I did have was getting the float spring in correctly...I had to take the carb back off and bck to the bench and pulled the top off. My issue was it would only run off of a bottle feeding from above it though...but that is a tricky lil pup getting it right is a make or break thing as I found out. If you happen to have a spare around, pull the top off and have a looksee if you need to.
- cs65
As to the pigtail snipping...the tail is about an inch long...I left about 1/4" on it.
- cs65
As to the pigtail snipping...the tail is about an inch long...I left about 1/4" on it.
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Joined: Jun 2009
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From: Portland,OR
Typical Auto-Lite/Motorcraft 2V carb problem.
Bogging down, stumbling, hesitating from a dead stop or when accelerating at speed: Defective accelerator pump diaphram and check valve.
Yes, you rebuilt the carb, and you prolly replaced the diaphram, but what about the check valve?
The check valve fits behind the diaphram, has a tiny nipple on one side that fits into a hole in the carb body. This nipple is notorious for snapping off...and because of this, you have to be very careful when installing it.
Bogging down, stumbling, hesitating from a dead stop or when accelerating at speed: Defective accelerator pump diaphram and check valve.
Yes, you rebuilt the carb, and you prolly replaced the diaphram, but what about the check valve?
The check valve fits behind the diaphram, has a tiny nipple on one side that fits into a hole in the carb body. This nipple is notorious for snapping off...and because of this, you have to be very careful when installing it.
I've been having these same problems. idles but dies w/ any throttle.
diaphragm looks good...
Cargo Master
Joined: Jul 2006
Posts: 3,014
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From: Concord, CA
Since the OP has a 66 352 with a Autolite 2100 then there is only 1 little check ball. I just rebuilt 3 of these carbs as spares and have them on the shelf bagged. The check ball is in the venturi booster with a short rod on top of it and then the hollow screw over that.
If the check valve is good and the diaphragm is in the correct way with the spring then , as someone asked, are all the narrow passageways blown out. There are a bunch of them and when you blip the throttle you are going to give a shot of gas through the venturi booster. Take that thing off and notice all those little holes that bring gas. You can soak a carb all you want but those passageways need to be blown out one way or another. I even use a small hypodermic syringe that I fill with carb cleaner and inject it through every opening. Should come out another opening freely.
If the check valve is good and the diaphragm is in the correct way with the spring then , as someone asked, are all the narrow passageways blown out. There are a bunch of them and when you blip the throttle you are going to give a shot of gas through the venturi booster. Take that thing off and notice all those little holes that bring gas. You can soak a carb all you want but those passageways need to be blown out one way or another. I even use a small hypodermic syringe that I fill with carb cleaner and inject it through every opening. Should come out another opening freely.
Cargo Master
Joined: Jul 2006
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From: Concord, CA
To be honest your carb doesn't look like any of my 2100's from the front as per your picture. All mine look like this:
Freshman User
Joined: Jun 2009
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From: Portland,OR
this is an old post that makes me sure it's original. does that mean it's not a 2100? if this carb doesn't have a red rubber check valve but has the same issue as described in this thread then what? must be something else.
tag is C3TF H B 3GC. the 3 I'm assuming is for '63
Quote:
Originally Posted by 64F-100 View Post
The tag on my carb reads: C3TF H B 4CC
Does it sound like this is the correct carb on this truck?
Yes.
C3TF-H = C3TZ-9510-U .. Carburetor (Motorcraft CA-271)
1957/63 & 1964/72 Ford Truck Parts Catalogs / Carburetor Parts List #14A
Original application: 1963/64 F100/700 292.
D4AZ-9A586-A .. Carb Kit (Motorcraft CT-499-D)
78-9533-B .. Carb Jet ~ #48: 0-5,000 ft. (Motorcraft CJ-55)
C1AZ-9533-B .. Carb Jet ~ #46: 5,000-10,000 ft. (Motorcraft CJ-20)
C1AZ-9533-F .. Carb Jet ~ #44: 10,000-15,000 ft. (Motorcraft CJ-24)
__________________
Bill / Retired Ford Parts Manager // Part number research: 1928/2002 Passenger Cars & Trucks.
tag is C3TF H B 3GC. the 3 I'm assuming is for '63
Quote:
Originally Posted by 64F-100 View Post
The tag on my carb reads: C3TF H B 4CC
Does it sound like this is the correct carb on this truck?
Yes.
C3TF-H = C3TZ-9510-U .. Carburetor (Motorcraft CA-271)
1957/63 & 1964/72 Ford Truck Parts Catalogs / Carburetor Parts List #14A
Original application: 1963/64 F100/700 292.
D4AZ-9A586-A .. Carb Kit (Motorcraft CT-499-D)
78-9533-B .. Carb Jet ~ #48: 0-5,000 ft. (Motorcraft CJ-55)
C1AZ-9533-B .. Carb Jet ~ #46: 5,000-10,000 ft. (Motorcraft CJ-20)
C1AZ-9533-F .. Carb Jet ~ #44: 10,000-15,000 ft. (Motorcraft CJ-24)
__________________
Bill / Retired Ford Parts Manager // Part number research: 1928/2002 Passenger Cars & Trucks.