Bad idle on Carter BBD finally solved!! - JeepForum.com
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post #1 of 13 Old 09-06-2019, 03:57 PM Thread Starter
only in a jeep cj
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Bad idle on Carter BBD finally solved!!

I never understood why people are so fast to replace the Carter BBD that came on the later CJ. I’ve been running one in some form or another on all my late CJ‘s for the last 27 years. They are very easy to rebuild and set up. Disclaimer, I am at sea level.

Anyway, mine went from running great to all of a sudden having an erratic idle, and just feeling really weird in between shifts or when there was no load on the system. Some days it was worse than others and there was no smoothness as before.

So I figured the idle tubes were gummed up or something of that nature. I rebuilt the carb just as I always have and there was no change afterward. The more and more it fiddled with it, the more I concluded it was acting like a vacuum leak. I messed with all of the hoses such as the vacuum advance, the power brake booster, choke plate diaphragm, PCV hose, etc. and got nothing. I pulled spark plugs, checked resistance in the plug wires, swapped the ignition module out, checked dist cap/button/ contacts, timing, sprayed the seals checking for idle change, etc....still nothing. . I drove this thing for three months, the whole time about to pull my hair out.

So I pull the carburetor off one more time to go back through it and check again. As I pulled it off of the mounting studs I looked down at the plastic spacer block between it and the manifold and thought to myself that I don’t believe I removed that spacer and checked it last time. The picture shows what I found under the spacer. Two new gaskets later, I have a steady idle and a smooth running engine.

So for those who might have a vacuum leak or an idle issue, don’t forget to check everywhere ....even the stuff that is hidden out of sight.

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Ed
1975 CJ-6 1983 CJ-8
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post #2 of 13 Old 09-11-2019, 11:40 AM
mc190
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I think that is the problems with Carter- when they have an issue, their hard to find out what the problem is. Don't get me wrong, the Carter Carb works great when it's dialed in. It's getting it dialed in, or finding the problem that gives it a bad wrap.


Spent last weekend doing a Carter BBD rebuild (well I did not do it, my son along with my father did it on the work bench). Got a nice kit from Mike's Carberator and a new choke spring so for $50 figured it's worth rebuilding the carb. As well as getting my son some first hand knowledge about how a carburetor works.


After the rebuild by dad, who was a mechanic/ wrench turner for years back in the 60-70's and has over 50yrs in the auto service industry, was telling my son that was not a easy carb to rebuild. I certainly was not going to argue with him about it.
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post #3 of 13 Old 09-11-2019, 07:59 PM
BagusJeep
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I struggled for years with mine until the accelerator plunger broke up. I got a clone from fleabay for one of my jeeps (which is crap) but it is standing instead of teh BBD which si now scheduled for a rebuild. the Weber 38 is better IMHO.

BagusJeep lives in Bali with far too many 4x4s:
1981 CJ7 258ci - Bagusjeep
1984 CJ7 258ci - Puthijeep
1981 J20 258ci - Gladys
1951 Willys CJ3A/MB/M38 - Little Willy
1995 Cherokee 4.0 - CHEROKEE
1980 Land Rover Series III 109" troop carrier - ROVER
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post #4 of 13 Old 09-11-2019, 08:21 PM
brianscoob
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I took on the Carter carb years ago and I just couldn't get it to run properly but it mind I wasn't going to be defeated, until I was. I put a Weber on and with hardly making any adjustments the engine just purred. Back them it was a huge expense to put a Weber on but I saved up the money and it was well worth it. Years later I rebuilt the Carter but I never put it back on. I think MC190 is right in that if you have the Carter dialed in you'll have no problems but it's a PITA if you don't. Crazy because I don't remember what I did with the Carter I took off and rebuilt?? It's been over 25 years probably.
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post #5 of 13 Old 09-12-2019, 03:54 AM
John Strenk
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We are still talking the difference of a new clean carb vs a home rebuilt worn out carb.

I put on a new BBD from National carb and I haven't had to touch it in 5 years now.

Starts right up with a twist of the key. Runs strong.

I think I counted some 30 openings in the carb and if only one of them gets clogged, it will cause problems.
Soaking them in carb cleaner after the passages get clogged doesn't usually work.
And then there is the wear around the throttle shafts to worry about.

I also wonder of the pump gas we are putting into our jeeps is worse than what these carbs were originally designed for.
I know my old lawn equipment runs great on non-alcohol gasoline. My jeep will probably run better also but it's too expensive to burn there.


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I drive a Prius to save money and buy more Jeep Parts....
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post #6 of 13 Old 09-13-2019, 07:09 PM
LumpyGrits
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Lots of good info here--
http://gleebledorf.com/

https://drive.google.com/file/d/1Y7Z...jiQxMna23/view

I for one like the Carter, and it's the only carb allowed for Ca. SMOG on our late model CJ's w/4.2L.

LG
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post #7 of 13 Old 09-13-2019, 07:37 PM
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Interesting! . . . and good to know!

I have actually been dealing with the same issue and it has been driving me crazy. The carburetor was replaced at previous smog; one year ago, but it never ran like the old OEM Carter BBD. After that OEM one was rebuild right, it ran smooth. This exchanged one never has? I have wondered if they gave me a knock-off but was too exhausted at the time to argue with the shop. The smog stuff I went through just wore me out at that time. I did get angry at the shop for replacing it rather that sending it to get properly rebuilt. Oh well.

Anyway, today I actually started tracing hoses, cleaning plugs, cap, etc. trying to look for my erratic idle issue. After everything I did, it runs better but not 100%. I will definitely take a look at the Carter base plate this coming week. I forgot what a smooth ride the Carter can produce, lol. . . . Thanks "only in a jeep cj" for that tip.

"LumpyGrits", you are 100% correct about CA only allowing the Carter. I'm still scratching my head about that!!!
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post #8 of 13 Old 09-14-2019, 05:05 AM
ddawg16
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I kept mine running well for about 15 years (bought the jeep in 94). My biggest issues were vac leaks in hoses and the charcoal canister. Oh, and the worn throttle plate shaft.

But.....going to a fuel injected SBC? No going back.

It's so nice to start on a steep hill....and not be flooded.


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post #9 of 13 Old 05-04-2021, 09:53 PM
pvw10121
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Jumping in on this thread to ask a question about my 89 Wrangler Carter bbd carb. I found this thread and it was very helpful... and obviously had some knowledgeable jeepers on it.

I've had my Jeep for almost 18 years. Other than the idle tubes getting clogged way too often... I've had pretty good luck with the bbd carb. I do have an issue right now that I'd appreciate your comments on.

My stepper motor went out on the carb... so, I went ahead and did a Nutter bypass on the jeep. I rebuilt the carb while I was working on it. Full rebuild. (not the first time I've rebuilt it).

Jeep starts fine... idles fine when sitting... runs fine while driving... but, when I push in the clutch to downshift... the jeep will die fairly quickly (sometime really quickly -almost immediate). If I clutch the jeep... and feather the accelerator a little to keep the RPMs up for a few seconds and let it lower toward idle slowly... the jeep will idle just fine. It is acting like clogged idle tubes but, I'm very aware of that issue and have unclogged the tubes many, many times. I've cleaned the tubes a couple times lately just to be sure.

Tubes are clean...
I've sprayed carb cleaner all around the carb and vac hoses and I'm pretty confident that I do not have a leak...
I did notice that my fuel filter was oriented wrong and fixed that (placing the return nozzle/port at 12 o'clock). *(when I first did this... it seemed to help. I thought I had found the issue... but, it was short lived -a few clutch cycles later and it started again.

Could this be a float adjustment issue?

Thoughts?

Thanks,
Pwells
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post #10 of 13 Old 05-05-2021, 08:06 PM
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My instinct it is a float issue or a fuel supply issue.

You have a stock mechanical pump?

Have you checked out the amount of fuel reaching the carb inlet? I take the hose off and pump into a jar whilst turning the engine, a healthy spurt every few seconds.

Then it may be a blocked inlet valve or sunk or sticking float or incorrectly set float.

I recall my mechanic had a trick of taking the top half of the carb off and starting the engine to see the floats in operation at idle.

BagusJeep lives in Bali with far too many 4x4s:
1981 CJ7 258ci - Bagusjeep
1984 CJ7 258ci - Puthijeep
1981 J20 258ci - Gladys
1951 Willys CJ3A/MB/M38 - Little Willy
1995 Cherokee 4.0 - CHEROKEE
1980 Land Rover Series III 109" troop carrier - ROVER
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post #11 of 13 Old 05-06-2021, 11:41 AM
pvw10121
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Hey BagusJeep.... -thanks for the quick reply. Wasn't sure if I'd get any bites.

I hope to piddle with the ole Jeep this this weekend. I'll look into float and/or fuel supply issues as you suggest. Yes, it does have a mechanical fuel pump. I last replaced it probably 10-12 years ago. May be time to replace it. It's also been a minute since I've replaced the fuel filter. I do the hose in a jar/bucket trick to to see the fuel flow.

I'll do some work this weekend and will update the thread afterwards.

I've spent the last few months trying to find Gronk... the 'ebay Jeep motorcraft carburetor guy'... -no luck... no response from him. I am about ready to go with the weber replacement. Sounds like you have some experience there, as well. Would you mind me ping'ing you on some weber questions and your thoughts/recommendations on the weber 38 at some point?
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post #12 of 13 Old 05-07-2021, 03:53 AM
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Ping me by all means, i have done a few.

They all ran sweet straight from the box, but there is a thread on here about tuning the Weber and the problems people have had. It is a great carb, well known, and Made in Spain.

Sometimes a real good clean will do it. I do mine over a basin as the little parts fall out and they are a bugger to find on the floor.

BagusJeep lives in Bali with far too many 4x4s:
1981 CJ7 258ci - Bagusjeep
1984 CJ7 258ci - Puthijeep
1981 J20 258ci - Gladys
1951 Willys CJ3A/MB/M38 - Little Willy
1995 Cherokee 4.0 - CHEROKEE
1980 Land Rover Series III 109" troop carrier - ROVER
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post #13 of 13 Old 05-08-2021, 05:34 AM
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I'm thinking float level. To confirm, pop it in neutral without touching anything else. When you downshift the fuel in the bowl goes forward. It might be enough to lean it out if the level is too low.

Also....any change in idle when you push on the brakes?

Having a vacuum gauge in the cab is one of the best instruments you can have for these engines.


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