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-   -   4.2 carb problems (http://www.wranglerforum.com/f218/4-2-carb-problems-13205.html)

stray 11-15-2007 12:18 PM

4.2 carb problems
 
I have an 89 Wrangler with a 4.2 six cylinder and I'm having persistent carburetor problems (stumbling, stalling, pinging at freeway speeds etc.) I've had no luck repairing it. Is there any tricks or aftermarke carburetors that are street legal in California ?

Grandpa Jeeper 11-15-2007 04:38 PM

Quote:

Originally Posted by stray (Post 158740)
I have an 89 Wrangler with a 4.2 six cylinder and I'm having persistent carburetor problems (stumbling, stalling, pinging at freeway speeds etc.) I've had no luck repairing it. Is there any tricks or aftermarke carburetors that are street legal in California ?

I was gonna steer you to the MC2100, but then I saw CALIFORNIA. Hell, nothings legal in CA anymore is it?

bernm8r 11-15-2007 07:45 PM

Same here,
I bought a MC2100 for mine and it has been running fantastic so far. I do need to finish my manual choke for these winter months but it still starts even cold no problem

Justin 11-15-2007 07:57 PM

bernm8r, where'd ya get the 2100 and how much did u get it for?

dadstoys2 11-16-2007 02:03 AM

I love my big Webber
I have heard the holleys are great too.
But in Ca I dont know what to tell you. There is a modification to fix its problem but I cant find the link.
~Rich

Teriod 11-16-2007 05:59 AM

http://home.sprynet.com/~dale02/list.htm

only way I can find to pass ca emmissions are tbi's either mopar or howell,, I havent seen any different carburetors that have CARB numbers

82shortbox 11-16-2007 10:08 AM

89 CARB,Kinda long but worked for my 88 for 4,000 miles and counting
 
Easy Fix for Jeep 258 Carter BBD Idle Problem




by Terry L. Howe




The Jeep 258 (4.2L) I6 isn't a power house, but it has gobs of low RPM torque that makes it a great engine off-road. The most common problem I see with the engine is it's inability to idle. Between the 258 in my '81 CJ-7 and a couple friends that have 258 equipped Wranglers, I have fixed this problem half a dozen times and the cause of the problem has always been the same. The problem has always been caused by clogged idle tubes that cause fuel to drip out of the venturis and make the Jeep run rich at idle. Fixing the problem is relatively easy and once you get past this problem, you will get much more enjoyment from the 258 and the Carter BBD carburetor.

The Carter BBD is a two barrel carburetor that was available on late 70s to late 80s Jeeps with the 4.2L engine. There are two variations of the carburetor, one is computer controlled and has a stepper motor on the back side. The computer controlled version was used after 1981. Other than that, the two versions are the same although it seems the stepper motor version is a bit more troublesome.

The Symptoms
The symptoms of the problem include stumbling and sputtering at idle. In advanced cases, the Jeep will stall at every stop sign and will only run at high RPMs. Gas mileage will suffer since fuel will just be sloshing out at idle. Sometimes the idle will be turned up to a high RPM to avoid the problem. Typically, the Jeep will run fine at higher RPMs (unless there are also other problems.)
For a sure diagnosis, park the Jeep with the engine off and remove the air cleaner cover. There should be a plate over the throat of the carb, the choke plate. If you open the choke plate you should be able to see down the throat of the carb and you should see two screws with holes in the middle of them. Next to them are two passages with a nozzle in the middle of each. This thing is known as the venturi, when air passes by, fuel is supposed to be drawn out through the nozzles. If the idle tubes are clogged fuel will drip from those nozzles during idle.

In order to see if fuel drips from the nozzles at idle, you must start your Jeep with the air cleaner cover off and look down the throat of the carb. The Jeep Technical Service Manual recommends that, when you do this, you cover the air cleaner with a piece of plexiglass since the engine can backfire through the carb and a flame can shoot out. Since I am reckless and like living dangerously, I never do this.

After you have chosen the wise or foolish path, start your Jeep and open the choke plate. If your idle tubes are badly clogged, you will see fuel dripping from the nozzles at idle (if your Jeep will idle at all.) If you don't see fuel dripping, but your idle is still poor, open the throttle a bit with your hand or have a friend hit the accelerator. You should see two even streams of fuel and no dripping from the nozzles. Any dripping means clogged idle tubes.

While you are doing this, make sure you don't put your hand or anything else into rotating parts like the fan. Keep your tie away from that thing (some people just want to look good all the time.) Same goes if you are a "long hair, freaky" Tesla type. All joking aside, I've heard some bad stories.



The Solution
Neither removal of the carburetor nor a complete rebuild is necessary to fix the problem. To fix the problem, start with you Jeep off and parked securely:
Remove the air cleaner cover and air cleaner. You may need to remove a few hoses and wires to get the air cleaner out of the way. Make sure you tag them all so you can put them back in the right spot. It's often easiest not to remove the heater hose that goes to the exhaust manifold, if you have one.
Remove hoop that holds air cleaner.
Remove the two screws holding the choke plate with a 3/16" socket or small flat blade screw driver depending on what screws you have holding it. Be careful not to drop the screws down the manifold unless you enjoy fishing. Remove the choke plate.
If your carb has one, remove the plate on the side that covers the choke linkage so you can access the screw holding the choke rod. It may be necessary to drill out a rivet to get it free.
Remove the little snap ring and screw (1/4" socket) that holds the rod that holds the choke plate and remove the rod. A screw driver will normally push off the snap ring.
Remove the two screws with holes in the middle of them and carefully remove the venturi cluster with the two little gaskets. There should be two idle pickup tubes pushed into the venturi sticking out of the bottom. If they have fallen out, that could cause your idle problem.
Blast the venturi and inside of carb with lots of carb cleaner. Be sure not to dislodge the check ball in the center.
With a long thin pin or piece of piano wire, make sure the idle tubes and nozzles are clear. After you have run them through, spray with more carb cleaner.
Put the cleaned out venturi cluster back with the two gaskets and two screws.
Replace the choke rod with snap ring and screw and replace the choke plate. Make sure all the screws are tight that hold together the carb body at this time. Often the screws will loosen up and dirt will be sucked into the carb.
Replace the plate covering the choke linkage with a sheet metal screw, or leave it off.
Replace the air cleaner.
Smooth idle should have returned after this simple process. If you still have idle problems and don't have any dripping, make sure all the vacuum hoses are hooked up and in good shape. Also check for leaks around the intake manifold or a loose carburetor.
To avoid repeated clogged idle tubes, drill out the idle tubes to 0.032". This will greatly reduce the frequency of clogging and it is a procedure that was actually recommended by Jeep for a while.

An alternative to removing the choke plate and all is to just remove the top of the carburetor. The advantage of this approach is you can make sure there isn't a lot of junk in the bowls, you can check your float adjustment, etc. It also may help if you have power brakes because the master cylinder may be in the way of getting the choke rod out.

Contributor
Thanks to Randy Peterson for posting this solution a few years back. I've used it on various Jeeps many times since.

dadstoys2 11-16-2007 01:11 PM

There is also a fix that involves drilling open the tubes or something.
I have an aftermarket so the details of this were never important to me. BUt I remember reading something else too.
~Rich

bernm8r 11-16-2007 03:12 PM

Justin I bought it from a guy on ebay (user name ehrmannmp)who has sold lots of em. Very nice setup and support. I paid I think $300 for the carb, air filter and shipping. His directions are easy and very in depth. I opted for the rear pulling throttle. it was an easy mod and makes it look a whole lot less convoluted with linkages. I tell you my Jeep has run fantastic since then I am so pleased.
Cheers,
Bern

ggrote1 01-20-2011 09:13 PM

I bought a rebuild kit from Auto Zone for my BBD Carter and it looked like enough parts for 3 carbs. I decided to just use the gaskets and try the Easy Fix and clean the pickups in the venturi as suggested by Randy Peterson. It seems to have worked great. I had to turn my idle back down to around 650 RPM after cleaning the carb and pickups. I could see trash in one as described. I made it a point to clean all the ports on the venturi very well and could see them clean up when I sprayed carb cleaner in, both directions, small holes and large holes to clean it all out. Took about one hour in poor lighting and on the dirt back yard. I would buy a carb kit to do it, about fifteen dollars,so you have all the gaskets and clips incase you drop anything. Thanks for the good idea, saved me a lot of bucks, now I can want a weber but don't have to buy one right away.....

drbandkgb 01-20-2011 09:46 PM

I went to a Holley and zero issues since

toby123 08-17-2011 08:11 PM

Quote:

Originally Posted by bernm8r (Post 159008)
Same here,
I bought a MC2100 for mine and it has been running fantastic so far. I do need to finish my manual choke for these winter months but it still starts even cold no problem

what is the mc2100

toby123 08-17-2011 08:17 PM

can i get a holly for my 88 wrangler or will i have to get an intake also?or do i get a weber ?i got the same problem at highway speeds as others here

Alex801 08-18-2011 04:15 PM

Quote:

Originally Posted by 82shortbox
Easy Fix for Jeep 258 Carter BBD Idle Problem

by Terry L. Howe

The Jeep 258 (4.2L) I6 isn't a power house, but it has gobs of low RPM torque that makes it a great engine off-road. The most common problem I see with the engine is it's inability to idle. Between the 258 in my '81 CJ-7 and a couple friends that have 258 equipped Wranglers, I have fixed this problem half a dozen times and the cause of the problem has always been the same. The problem has always been caused by clogged idle tubes that cause fuel to drip out of the venturis and make the Jeep run rich at idle. Fixing the problem is relatively easy and once you get past this problem, you will get much more enjoyment from the 258 and the Carter BBD carburetor.

The Carter BBD is a two barrel carburetor that was available on late 70s to late 80s Jeeps with the 4.2L engine. There are two variations of the carburetor, one is computer controlled and has a stepper motor on the back side. The computer controlled version was used after 1981. Other than that, the two versions are the same although it seems the stepper motor version is a bit more troublesome.

The Symptoms
The symptoms of the problem include stumbling and sputtering at idle. In advanced cases, the Jeep will stall at every stop sign and will only run at high RPMs. Gas mileage will suffer since fuel will just be sloshing out at idle. Sometimes the idle will be turned up to a high RPM to avoid the problem. Typically, the Jeep will run fine at higher RPMs (unless there are also other problems.)
For a sure diagnosis, park the Jeep with the engine off and remove the air cleaner cover. There should be a plate over the throat of the carb, the choke plate. If you open the choke plate you should be able to see down the throat of the carb and you should see two screws with holes in the middle of them. Next to them are two passages with a nozzle in the middle of each. This thing is known as the venturi, when air passes by, fuel is supposed to be drawn out through the nozzles. If the idle tubes are clogged fuel will drip from those nozzles during idle.

In order to see if fuel drips from the nozzles at idle, you must start your Jeep with the air cleaner cover off and look down the throat of the carb. The Jeep Technical Service Manual recommends that, when you do this, you cover the air cleaner with a piece of plexiglass since the engine can backfire through the carb and a flame can shoot out. Since I am reckless and like living dangerously, I never do this.

After you have chosen the wise or foolish path, start your Jeep and open the choke plate. If your idle tubes are badly clogged, you will see fuel dripping from the nozzles at idle (if your Jeep will idle at all.) If you don't see fuel dripping, but your idle is still poor, open the throttle a bit with your hand or have a friend hit the accelerator. You should see two even streams of fuel and no dripping from the nozzles. Any dripping means clogged idle tubes.

While you are doing this, make sure you don't put your hand or anything else into rotating parts like the fan. Keep your tie away from that thing (some people just want to look good all the time.) Same goes if you are a "long hair, freaky" Tesla type. All joking aside, I've heard some bad stories.

The Solution
Neither removal of the carburetor nor a complete rebuild is necessary to fix the problem. To fix the problem, start with you Jeep off and parked securely:
Remove the air cleaner cover and air cleaner. You may need to remove a few hoses and wires to get the air cleaner out of the way. Make sure you tag them all so you can put them back in the right spot. It's often easiest not to remove the heater hose that goes to the exhaust manifold, if you have one.
Remove hoop that holds air cleaner.
Remove the two screws holding the choke plate with a 3/16" socket or small flat blade screw driver depending on what screws you have holding it. Be careful not to drop the screws down the manifold unless you enjoy fishing. Remove the choke plate.
If your carb has one, remove the plate on the side that covers the choke linkage so you can access the screw holding the choke rod. It may be necessary to drill out a rivet to get it free.
Remove the little snap ring and screw (1/4" socket) that holds the rod that holds the choke plate and remove the rod. A screw driver will normally push off the snap ring.
Remove the two screws with holes in the middle of them and carefully remove the venturi cluster with the two little gaskets. There should be two idle pickup tubes pushed into the venturi sticking out of the bottom. If they have fallen out, that could cause your idle problem.
Blast the venturi and inside of carb with lots of carb cleaner. Be sure not to dislodge the check ball in the center.
With a long thin pin or piece of piano wire, make sure the idle tubes and nozzles are clear. After you have run them through, spray with more carb cleaner.
Put the cleaned out venturi cluster back with the two gaskets and two screws.
Replace the choke rod with snap ring and screw and replace the choke plate. Make sure all the screws are tight that hold together the carb body at this time. Often the screws will loosen up and dirt will be sucked into the carb.
Replace the plate covering the choke linkage with a sheet metal screw, or leave it off.
Replace the air cleaner.
Smooth idle should have returned after this simple process. If you still have idle problems and don't have any dripping, make sure all the vacuum hoses are hooked up and in good shape. Also check for leaks around the intake manifold or a loose carburetor.
To avoid repeated clogged idle tubes, drill out the idle tubes to 0.032". This will greatly reduce the frequency of clogging and it is a procedure that was actually recommended by Jeep for a while.

An alternative to removing the choke plate and all is to just remove the top of the carburetor. The advantage of this approach is you can make sure there isn't a lot of junk in the bowls, you can check your float adjustment, etc. It also may help if you have power brakes because the master cylinder may be in the way of getting the choke rod out.

Contributor
Thanks to Randy Peterson for posting this solution a few years back. I've used it on various Jeeps many times since.

I had a question regarding this post. I have the exact problem that is described above. Although I know for a fact my choke on my Carter BBD carburetor in my 88' YJ is not working properly. I have not checked my idle tubes to see if they are clogged. But since I'm experiencing a couple problems with my carburetor I was wondering if a carb rebuild would fix my idle tubes and also my choke? And any other I may have? Or do I need to purchase maybe new parts for repair that do not come with a rebuild kit? ,Alex

daddyjeep 08-18-2011 10:31 PM

You can put a 2 barrel or 4 barrel Holley on a YJ intake. You will just have to buy an adaptor plate. I ran a Holley on mine for a while until I went with the Howell Fuel Injection. It was a bit pricy, but the best money I ever spent on my Jeep.

Alex801 08-18-2011 10:48 PM

What are the price differences between the holleys and the Howell? Also what are the performance differences? (Sorry I'm new to carburetors and what not)

Missouri Bound 08-19-2011 07:55 PM

I bought the Weber Redline K551 kit. Great upgrade, do not know if California will accept the retrofit.

ndnbrav 09-20-2011 03:50 AM

I used to tinker with my old carb all the time, then one day got tired of it and bought the Howell TBI carb legal for California, and now I have more time behind the wheel than in the engine!

mrksbby 12-27-2011 05:39 PM

All of this information is great would it apply to a single barrel carb as well? My 4.2L has the single barrel model and it dies when it gets hot.

toddj 09-29-2014 12:33 PM

there is a lot of helpful info here but my problem is a little different I think. mine looks like it has an auto choke set up on it and its stuck open if I remove the e clip it will close and run as long as you work the choke manually. my jeep is an 86 cj7 has anyone else had this problem, and what did you do for it

Nubby55 09-29-2014 10:02 PM

Quote:

Originally Posted by toddj (Post 13739090)
there is a lot of helpful info here but my problem is a little different I think. mine looks like it has an auto choke set up on it and its stuck open if I remove the e clip it will close and run as long as you work the choke manually. my jeep is an 86 cj7 has anyone else had this problem, and what did you do for it

The electric choke does not come in most kits, you can buy it at a parts house for about $50.00 and it is $ well spent for the choke to work, you will have to adjust it but then that maybe all you need to do not, try to adjust it first. {Cold}


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