- Carter AFB, AVS Flooding
- My AFB Idles Too Fast
- Troubleshooting AFB Low Speed Circuit
- AFB - Adjusting Idle Mixture Isn't Changing the RPM
- Why my Carter AFB Doesn't Idle Well?
- AFB Hesitation
- AFB- Pouring Gas Down Carburetor. It only runs a few seconds.
Do you know what side the brass insert is suppose to face...toward each other like I have it?
No, they should be to the outside.
I have a 1967 Chrysler Carb that has 2 pins holding the air adjustment screws in I have a broken Air adjustment screw due to someone trying to back out the screw without removing pin, Now I need to remove pin to get broken part out, Have you ever dealt with the pins, do you know what fits them to remove them
First of all it needs to be either heated up or very well lubricated. The pins have a very small Allen head.
First of all it needs to be either heated up or very well lubricated. The pins have a very small Allen head.
I have a 625 cfm Carter and it is idling rough and I can take the left fuel mixture screw all the way out while it is running and no change on the idle or rpm and still idling rough until I push on the throttle just a little and then it will clean up and run smoothly until I let off?
From what you describe I suspect you have a clog somewhere in the idle circuit, on the side you refer to. Take the idle mixture screw out and blow through the hole. They are small and can easily get clogged. From there find the passage way going to the idle mixture screw. Use thin wire to clean it out if you can. While you are at it inspect the screw for any grooves.
You didn't mention if you rebuilt the carburetor. That would be a good place to start if you haven't already.
Can I use the pointed check weight above the check ball?
Do not put the pointed check weight with the check ball. If it even fit, it would be too heavy and you would get a hesitation when throttling up.
A check ball would have a small weight, or spring above it. The pointed check weight is used without a check ball. The AFB came either way. You can also try using a check ball above the 1st check ball. This is usually enough weight.
Test by putting fluid in the accelerator pump well. Hold down either the check ball system, or the check weight system with a brass drift punch. Push the accelerator pump down the well. You should feel a bit of pressure and little if any fluid will come out of the main discharge.
If you get no pressure, then try the other setup (check ball, or pointed check weight). If still no pressure use a brass drift punch against the check ball, or weight and tap gently a few time to seat it.
Bogs down when I floor the pedal.
Does it have a choke, it's possible the choke may not open all the way not allowing the secondary's to open properly, also the passage's in the secondary cluster's are they clear, need to make sure there not clogged. Could be lots of things, needs to check compression also.
No Fuel
I rebuilt a Carter AFB Performance Plus carb and it ran fine for about 3 weeks. Then it would not start unless you primed it by spraying fuel into it and cranking the engine for awhile. Then it would start and run, but the next day no good and had to repeat process. Replace fuel filter and we get a very good stream of fuel when cranking from the hose between pump and carb.
Do you have and suggestions on what to do.
Could be a lot of things.
Plugged fuel filter.
Do you have and suggestions on what to do.
Could be a lot of things.
Plugged fuel filter.
Needle & seat sticking.
Float sticking.
Float sticking.
After turning the engine off look down the carburetor to see if gas is dribbling out of the venturi. If so, then you have a leaky main discharge. Is the check ball, weight, or spring in place? Test the accelerator pump circuit to see if it is leakiing. A leaky discharge will empty the fuel bowl and add too much gas to the intake making it hard to start.
Low fuel pump pressure.
It is possible that the fuel is running back toward the fuel pump when you turn it off. That would be the needle & seat.
Low fuel pump pressure.
It is possible that the fuel is running back toward the fuel pump when you turn it off. That would be the needle & seat.
Make sure the fuel tank vent is open. Some have an extra vent tube and some vent via the gas cap.
Could be percolating - engine gets hot, turn the engine off and fuel boils and evaporates.
My secondary jets have no acceleration tubes or any other plumbing underneath. Is this normal?
Yes, it is on some. Not all have tubes.
This is a problem that one of our customers reported to us along with the email conversations.
Sorry to bother you. I bought kit 4011 for my 1958 Cadillac Eldoradro, Carter 2862S AFB carb. Can't get car to come off idle, wants to die. Warm, choke off. Idles O.K., 500-850 RPM O.K. But when I push the accelerator to increase the RPM's above 850, it wants to die. If I coax it past this spot, at higher RPM's it seems fine. A stream of fuel comes out the two accelerator pump jet nozzles when I depress the throttle, so I think the accelerator pump is O.K. I've adjusted the two mixture screws. There is a big air adjustment screw located between the two idle mixture screws, I tried to adjust that also. (But I don't actually know the procedure for this air adjusment) Once it starts getting past the stumble, I notice drops of fuel coming out of the primary venturi's, and dropping down onto the throttle buterflies. (I would think it would be atomized, not drops?) I've disassembled the carb a couple times, the float bowls are about 1/2 full. I'm stumped, I didn't have this problem before I rebuilt the carb. I didn't remove any shafts or butterflies. I would appreciate any ideas you have to offer. Second update: I should have checked this before I sent My first e-mail. My problem is a lean condition. If I pour a lttle gas down the carb while it is stumbling, it stops stumbling and smooths out. So the question is: What causes a just above idle lean condition? Third update: I fully closed the big air adjustment screw located between the two idle mixture screws, and this helped alot. I moved the accelerator pump rod down to the bottom hole, and this seemed to help some. I stll have an off-idle stumble, but it's drivable, it doesn't try to stall, just stumbles. The stumble is smooth slow acceleration, not punching it.
Solution
I took it apart again, and found a piece of debris partially plugging the small brass tube feeding fuel to the primary venturi, (the small tube inside the bigger tube with holes in it) The clue was, just above idle fuel would drip out of one venturi, (the bad side) No more hesitation, and I was able to open the air adjustment screw to set the idle speed.
Dual set up running rich and secondary problem.
No ID on these carbs but I believe they came off an early 60's Pontiac. Dual AFB's on Weiand manifold on a 1957 Chrysler 392 Hemi, probably the 325 hp model.
Engine runs fine but when I recently pulled the plugs they are all black, rich. I was thinking if I could put smaller primaries in that would help the rich mixture.
After reading your info on your website I went out and pulled the metering jet and the primary and secondary jets. The primary jet measures 0.090, the metering rod is about 0.080 in the middle and 0.060 on the end. The secondaries are about 0.070 for what it's worth.
Maybe one other question while I've got your attention. See if what I see makes sense. First there are no chokes. The rear carb is primary and as the throttle begins to open at about half throttle the forward (secondary carb) linkage begins to open. I'm assuming the rear (primary carb) secondaries will begin to open from vacuum at that point. Then at about 3/4 throttle the vacuum secondaries on the front (secondary carb) begin to open as well. I don't know of a way to confirm the action of the vacuum secondaries. Does that sound right?
Engine runs fine but when I recently pulled the plugs they are all black, rich. I was thinking if I could put smaller primaries in that would help the rich mixture.
After reading your info on your website I went out and pulled the metering jet and the primary and secondary jets. The primary jet measures 0.090, the metering rod is about 0.080 in the middle and 0.060 on the end. The secondaries are about 0.070 for what it's worth.
Maybe one other question while I've got your attention. See if what I see makes sense. First there are no chokes. The rear carb is primary and as the throttle begins to open at about half throttle the forward (secondary carb) linkage begins to open. I'm assuming the rear (primary carb) secondaries will begin to open from vacuum at that point. Then at about 3/4 throttle the vacuum secondaries on the front (secondary carb) begin to open as well. I don't know of a way to confirm the action of the vacuum secondaries. Does that sound right?
I believe that if there are no chokes that these are off a Chrysler. As for it being rich that could be that they may have been sitting for too long or the floats are sticking, could be a lot of reasons. I would think Sirius about leaning them down. As for the secondary’s they are both mechanical and vacuum operated and it is a progressive type linkage.
Taller jets
My AFB has taller jets than those currently available, is this an issue?
No, you can use the standard replacement jets, just be sure the orifice size is the same.
What is the vent pointed to in the illustration.
When I disassembled there was no check ball in accelerator pump circuit, only the brass weight under the discharge nozzle assy
If the check weight has a pointed end, then it acts as a check ball and weight. No ball is necessary.
There is no check ball in the bottom of my accelerator pump well.
Your AFB probably has a check valve near the bottom of the float bowl next to the pump well. This is the inlet check.
When I pump the accelerator the main discharge doesn't spray until the throttle is partially opened.
One common problem often overlooked is the electrical system. The distributor advance in particular. Make sure it is operating as it should.
A list of possible problems (not in any order):
- Not enough fuel in the pump well. If the intake check isn't working as it should it may not be filling in the well. There is an inlet check in the bottom of the float bowl and it has a check ball in it. Take it out and make sure the check ball rattles around.
- The accelerator pump cup rolled up when being installed. A pump should be twisted in a circle while putting it in the well so it doesn't curl up.
- Pump cup has been damaged by ethanol, or some other chemical that is in the gas. We recommend using Ethanol Defender.
- The wrong accelerator pump was installed. The carburetor kit should be matched up with the carburetor number to insure it is the correct pump.
- The linkage going to the accelerator pump is loose, or perhaps bent so that it doesn't push the pump down right away. Operate the linkage and watch the pump action closely.
- The accelerator pump circuit is partially plugged and gas gets through only with maximum pressure.
Running rich after rebuild
- Since it was running OK before we can rule out the metering rods and main jets.
- Make sure the passages from the idle mixture hole and the off idle above it go all the way through the venturi's. The small holes on top of the venturi is what you are looking for. Look at the off idle video to gain some knowledge on how that works.
- If the carburetor was sitting for many months, or years I would highly suspect a plugged passage. Look at every hole you can find and test by blowing air through the hole.
- Look down the carburetor at idle. Do you see fuel dribbling out of the venturi. If so, then that is probably the problem. The main discharge may be leaking. There will be a check weight in the discharge hole (with pointed end), or perhaps a check ball and a spring above that. Depends on the vintage of the AFB. Take the carburetor off and test the accelerator pump circuit. The small holes on the venturi can get plugged easily.
- It isn't unusual for the venturi gaskets to need to be trimmed a bit so they sit flat. If they don't sit flat fuel will leak into the bore.
- Test the needle & seat. It is possible that while adjusting the floats pressure was put on the viton tip damaging it. It isn't unusual to get dirt into the needle & seat after rebuilding.
- Be sure the floats are centered. Move them up and down to feel any catching.
As with flooding, too much fuel is getting into the float bowl, or extra gas is getting siphoned into the bore because of a plugged air vent.
Not Idling Well & Center Mixture Screw Doesn't Make a Difference.
Not all AFB have the center adjusting screw.
Well the fact that it does the same thing with 2 different carbs tells me to look at electrical 1st.
Compression test might reveal 1 or more low cylinders which will cause an idle problem for sure.
I wouldn't discount a vacuum leak that hasn't been found yet.
The center screw not making a diff is worrisome. That smells of a vacuum leak to me.
Double check the mounting gasket to be sure it isn't leaving some port exposed causing a leak.
Spray carb cleaner around all vacuum sources and mounting gasket. A change in rpm tells you that you found the problem.
Why Does My AFB Idle Too Fast?
Take the carburetor off and back the idle screw out until it doesn’t hit the cam.
Look at the throttle valves to make sure they close all the way. Very little light will shine through. If they have been put in the wrong way, then they may not be sealing.
Make sure the fast idle screw is not touching the cam when the engine is warm and the choke valve is all the way open.
Most likely something is holding the throttle valves open.
Gas is Dribbling out of the Secondary at Idle
There are two places the gas could be coming out.
1. Gas leaking out of the venturi
2. Gas is leaking into the side of the secondary throat - Most likely the carburetor is warped, or the bowl gasket is wrong, or not fitting correctly thus allowing gas to slop over the side of the bowl and into the secondary.Gas is probably being siphoned - you need to blow through each small passage way on the venturi and where the venturi mounts to make sure there is no blockage. Spraying spray carb cleaner is a good thing to try. Be sure to wear goggles or you will get it in your eyes. Check the gasket to be sure it is installed in the correct direction and that the edges aren't curled up. Some need to be trimmed.
Hesitation or Bog
When pressing down on the gas pedal, the engine hesitates then begins to catch up.
This could be caused by the distributor, but we will only address the carburetor.
Hesitation is generally due to the accelerator pump circuit.
- The pump could be bad - replace it.
- With the engine off look down the carburetor and pump the gas. You should see 2 good squirts coming out of the main discharge. - If you don't get 2 equal squirts then one or more passages are plugged. Spray carburetor cleaner through each small passage, including any on #31 & #36. Make sure the spray goes through each passage. Ethanol can leave residue cleaners will not get out.
- Remove the pump jet housing. With fluid in the pump well, press down on the accelerator pump. Fluid should rush out of the main discharge. If it does, then the passage way from the pump well to the main discharge is OK.
- The check ball in the main discharge may not be working or missing - There should be a check ball and a spring, or a check ball and a check weight, or a check weight with a pointed end. See # 37 in the illustration. Depends on which AFB you have.
- Maybe the check weight, or check ball isn't sealing - Hold down the check ball or check weight with a brass drift punch and press down the accelerator pump with fluid in the carburetor. We use mineral spirits. You should feel some pressure which means the check ball is doing it's job. - If you get a leak, tap on the check ball a few times with the brass punch. It doesn't take much pressure to form a seat for the check ball.
- Make sure the gasket under the pump housing #36 fits flat. Sometimes a new gasket will need to be trimmed so that it lays down flat.
- There is an off idle circuit that is often missed. Look for a hole just above the idle mixture hole inside the bore. Blow air through the hole to see if air gets all the way through to the top of the carburetor. This is used when transferring from idle to the accelerator pump circuit and can cause some hesitation.
Hard Starting
The Carter AFB carburetor may experience hard starting due to a variety of issues. Some common causes include:
-
Dirty or clogged carburetor: Over time, the carburetor can become clogged with debris and dirt, making it difficult for fuel to flow properly and resulting in hard starting.
-
Incorrect choke adjustment: If the choke is not adjusted properly, it can prevent the engine from receiving enough fuel and air to start. When cold make sure the choke valve is closed. You need to press the gas pedal once when 1st starting. This does 2 things. Allows the choke valve to close and squirts a bit of gas into the carburetor which is needed on a cold start. When cold you can look down the carburetor and press the gas to make sure there is a squirt.
-
Faulty fuel pump: A malfunctioning fuel pump can cause insufficient fuel delivery to the carburetor, making it difficult to start the engine.
-
Worn out spark plugs: Worn out or fouled spark plugs can make it difficult for the engine to start, as the spark needed for ignition may be weak or nonexistent.
-
Low fuel pressure: If the fuel pressure is too low, the carburetor may not receive enough fuel to start the engine.
-
Faulty ignition system: A malfunctioning ignition system can prevent the spark needed for ignition from reaching the spark plugs, resulting in hard starting.
-
If the hard starting is after a run and the engine is hot then it might be the main discharge is leaking gas into the intake with the engine off. You would then need to over crank to start. After turning off the hot engine look down the carburetor to see if gas is dribbling from the venturi. If so, then the discharge is leaking, emptying the bowl . Look here on how to test the discharge.
