Carter BBD too rich... how to lean? - JeepForum.com
 
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post #1 of 13 Old 01-14-2010, 09:40 PM Thread Starter
HighFive
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Carter BBD too rich... how to lean?

I have the Carter BBD and have alot of black residue coming out of the exhaust. Pulled the plugs and they are black. When i give it hard throttle at idle it stumbles for a second then catches up. I think it is running too rich. So how do you lean out the fuel mixture?

Thx in advance!Oh and the accelerator pump is working properly too..


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post #2 of 13 Old 01-15-2010, 03:11 AM
John Strenk
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First I would get a vacuum gauge and check the vacuum to see if there are any leaks. Could be gaskets or old vacuum hoses or caps.

If the vacuum is too low in the manifold then the BBD thinks the engine is under load and it will richen the mixture on it's own.

So before you touch a screw, check you vacuum and fix any leaks.


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post #3 of 13 Old 01-15-2010, 06:42 AM
Mike Romain
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I will second that. The intake manifold bolts are notorious for coming loose.

Is your EGR plumbed right so it only comes on when the engine is fully warmed up and under throttle?

Has anyone messed with the internal carb settings or the front mix screws?

How old is the distributor cap and rotor?

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post #4 of 13 Old 01-15-2010, 09:27 AM Thread Starter
HighFive
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The egr valve and all emissions are stripped. all that is on it are vacum advance, line going to the charcoal canister, PCV, and bowl vent.

I sprayed carb cleaner everywhaere and there are no leaks in the manifold or carb base.

Before i was able to run it by setting the float level real high but then the problem started coming back so i set the float level to the correct size and have the idle screws 1 1/2 turns out. When i ad a little choke i can gun the throttle, but when the choke plate is open and i gun it it stumbles then picks up.

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post #5 of 13 Old 01-15-2010, 10:22 AM
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I had a simulator problem with a previous jeep, with a BBD and it would almost NOT run at high altitude. The PO had installed cheep after market air cleaner......about 5in diameter and 2in tall. It ran good with the air cleaner off. Soooooo, I found an OEM air cleaner and it ran good after that.

From that:
see how it runs without the air filter (but only for a very short time on paved roads, like one day if conditions are not dusty)

you might check to see if your filter is clean or needs to be changed,

if you dont have the OEM air cleaner maybe get one,

make sure there is no other restrictions (like debris in the snorkel).

The BBD is bad about building up carbon, and needs to be cleaned up from time to time. Here is a link for that: Easy Fix for Jeep 258 Carter BBD Idle Problem - - Jeep at Off-Road.com


If you do decide to change the jetting, I believe that you change the metering rods and not the jets.
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post #6 of 13 Old 01-15-2010, 10:42 AM
Fjguercio
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Running large mud tires 35" and 2.73 gears is a lugging / load type situation.

Rich setting will may help protect engine from detonation... so may want to consider leaving it rich.

Get lean, hot and lug and you may kock and detonate often
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post #7 of 13 Old 01-15-2010, 11:04 AM
John Strenk
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Quote:
Originally Posted by HighFive View Post
The egr valve and all emissions are stripped. all that is on it are vacum advance, line going to the charcoal canister, PCV, and bowl vent.

I sprayed carb cleaner everywhaere and there are no leaks in the manifold or carb base.

Before i was able to run it by setting the float level real high but then the problem started coming back so i set the float level to the correct size and have the idle screws 1 1/2 turns out. When i ad a little choke i can gun the throttle, but when the choke plate is open and i gun it it stumbles then picks up.

Did you pull the CTO valve off also?
How did you connect the Charcoal Canister?
If you open the canister before it warms up then you will be getting the wrong mixture.

Adding a little choke and having it work OK is a sign that it's running too lean. Might be a leak, Plugged passage in the carb. Something a simple as a partially plugged accelerator pump. Fuel level could be off....

Opening the charcoal canister to early could also make it run lean depending if there are any gas fumes to suck in.

Try clamping shut the Charcoal canister and see if that helps.


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post #8 of 13 Old 01-15-2010, 12:11 PM Thread Starter
HighFive
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Quote:
Originally Posted by Fjguercio View Post
Running large mud tires 35" and 2.73 gears is a lugging / load type situation.

Rich setting will may help protect engine from detonation... so may want to consider leaving it rich.

Get lean, hot and lug and you may kock and detonate often
This problem happens at idle. So that is out of the question.

Quote:
Originally Posted by John Strenk View Post
Did you pull the CTO valve off also?
How did you connect the Charcoal Canister?
If you open the canister before it warms up then you will be getting the wrong mixture.

Adding a little choke and having it work OK is a sign that it's running too lean. Might be a leak, Plugged passage in the carb. Something a simple as a partially plugged accelerator pump. Fuel level could be off....

Opening the charcoal canister to early could also make it run lean depending if there are any gas fumes to suck in.

Try clamping shut the Charcoal canister and see if that helps.
John, i clamped the canister line but nothing happened. Also the plugs are black. And today i took the carb off and cleaned it out again. But when i pulled it off there was alot of fuel sitting in the intake manifold. Is that a problem? Im just thinking that the engine is too rich and fouling the plugs. I am really confused with this carb. Thanks for the help to.

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post #9 of 13 Old 01-15-2010, 07:25 PM
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HighFive, Fjguercio means under normal driving conditions you have a lugging/ load condition that will cause your engine to run rich. A 4.2 does not turn high rpm's as it is so over time geared as you are you will foul your plugs. That said, if you have gas puddling in the intake rebuild the carb, you can't compress liquid, lol
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post #10 of 13 Old 01-15-2010, 09:07 PM Thread Starter
HighFive
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Quote:
Originally Posted by retrofit9 View Post
HighFive, Fjguercio means under normal driving conditions you have a lugging/ load condition that will cause your engine to run rich. A 4.2 does not turn high rpm's as it is so over time geared as you are you will foul your plugs. That said, if you have gas puddling in the intake rebuild the carb, you can't compress liquid, lol
Is there a specific problem that would cause the carb to put out too much fuel? There was alot of unburned gas in te intake. Ive been testing it at idle too. I took the carb apart today and cleanedd it out and checked the float level.

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post #11 of 13 Old 01-16-2010, 03:53 AM
John Strenk
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Well too much fuel and have it sitting on the floor of the manifold is one thing. Just too rich is another.

Is the gas in the manifold just after you have driven it or say it sat overnight?

It could be something a simple as a loose screw holding the throttle plate to the body or a plugged air bleed allowing the idle circuit to siphon out the gas out of the bowl when sitting still. A blocked air bleed will also make it run rich.


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post #12 of 13 Old 01-16-2010, 05:34 AM
Mike Romain
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Needing some choke to accelerate means you are running too lean or the accelerator pump is just plain worn out.

Gas pooling inside the manifold usually means the float needle is worn out which will blacken the plugs.

I would recommend you put a carb kit in it. They run about $20.00 and come with a new float needle and seat as well as a new accelerator pump. The kit also has the right settings for things.

Have you played with any other internal settings besides the float level?

Did you block off the line from the charcoal canister to the PCV purge line to see if the idle changes?

Mike
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post #13 of 13 Old 01-16-2010, 10:35 AM Thread Starter
HighFive
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Quote:
Originally Posted by John Strenk View Post
Well too much fuel and have it sitting on the floor of the manifold is one thing. Just too rich is another.

Is the gas in the manifold just after you have driven it or say it sat overnight?

It could be something a simple as a loose screw holding the throttle plate to the body or a plugged air bleed allowing the idle circuit to siphon out the gas out of the bowl when sitting still. A blocked air bleed will also make it run rich.
The gas in the manifold was there when i pulled the carb off after tinkering with the thing at idle. What is an air bleed and where is it at in the carb?

Quote:
Originally Posted by Mike Romain View Post
Needing some choke to accelerate means you are running too lean or the accelerator pump is just plain worn out.

Gas pooling inside the manifold usually means the float needle is worn out which will blacken the plugs.

I would recommend you put a carb kit in it. They run about $20.00 and come with a new float needle and seat as well as a new accelerator pump. The kit also has the right settings for things.

Have you played with any other internal settings besides the float level?

Did you block off the line from the charcoal canister to the PCV purge line to see if the idle changes?
I did block the charcoal canister and nothing changes. I think im just going to get a kit like you suggested.

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