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Car Forum / Jeep / February 2007CJ 7 Carb Problems
I need help with an '83 cj7 6cyl, 2bbl carb. I just had the carburator rebuilt. The jeep runs great untill I hit 4th gear. It seems like its flooding out, or like I dont have enough rev's to be in that high a gear. (I get only about 9 mph) I replaced the choke pulloff with no change. Vacum lines seem to be good. This happens wether the engine is hot or cold. Any help woulg be great. How did it drive before? When it warms up, is the choke open and the plate held fairly solidly in place? Other than that I would suspect maybe the throttle linkage is in the wrong hole for the accelerator pump and vacuum piston rod so it over-centers them at full throttle. It needs to be on the inner lever's hole by the finger lifter. Next I would suspect the carb base plate got in upside down maybe. The emissions stuff is still working right? If it isn't, then I would point you to other things. You are getting crap for mileage, mine gets about 23 mpg highway. Mike 86/00 CJ7 Laredo, 33x9.5 BFG Muds, 'glass nose to tail in '00 88 Cherokee 235 BFG AT's Canadian Off Road Trips Photos: Non members can still view! Jan/06 http://www.imagestation.com/album/pictures.html?id=2115147590 (More Off Road album links at bottom of the view page) > I need help with an '83 cj7 6cyl, 2bbl carb. I just had the > carburator rebuilt. The jeep runs great untill I hit 4th gear. It > seems like its flooding out, or like I dont have enough rev's to be in > that high a gear. (I get only about 9 mph) I replaced the choke > pulloff with no change. Vacum lines seem to be good. This happens > wether the engine is hot or cold. Any help woulg be great. What's the oil smell like, I wonder. My first check would be to make sure the choke plate is wide open when warm, the second would be to see if the float is stuck open. Either failure is going to dump gas into the oil. > How did it drive before? > [quoted text clipped - 26 lines] >> pulloff with no change. Vacum lines seem to be good. This happens >> wether the engine is hot or cold. Any help woulg be great. -- "We began to realize, as we plowed on with the destruction of New Jersey, that the extent of our American lunatic fringe had been underestimated." Orson Wells on the reaction to the _War Of The Worlds_ broadcast. When my float is stuck, it drips gas out the carb at idle and really messes up under 2000 rpm. If the stepper motor isn't running and it's pins are set wrong he will have the exact symptoms he describes also which is why I asked about emissions systems. Mike > What's the oil smell like, I wonder. My first check would be to make > sure the choke plate is wide open when warm, the second would be to see [quoted text clipped - 31 lines] >>> pulloff with no change. Vacum lines seem to be good. This happens >>> wether the engine is hot or cold. Any help woulg be great. My vote is for the "stepper motor" enrichment system also! When built, they were worried about NOX emissions caused by lean mixtures. That stepper dumps fuel into the carb when the Oxygen Sensor detects lean mixture. On a 25 year old vehicle with 100 feet of vacuum lines that operate everything, you may never find it. A thread tap and a couple of set screws blocking the enrichment system permanently cured mine while keeping everything under the hood looking "correct". I had 30 years experience with the Carter BBD and they always ran flawlessly, so I knew there was a "monkey in the works" somewhere. Sure enough, good old Uncle EPA forced Carter to ruin their design by adding that stepper . After the "retro" modification, my jeep now runs absolutely perfect. Instant starts hot or cold, 20 mph in high gear and you can floor the accelerator and get a smooth speed up. And running 65 to 75 on the Interstate, it gets 15 to 16 MPG. I just did a 200 mile round trip yesterday (with the top off-Yeah!) so that is verified mileage. Another good modification that is also reversable if you ever need to is the "Nutter Bypass", it completely "retros" your ignition to the reliably simple 70's version. http://www.4x4wire.com/jeep/tech/electrical/jn-ignition99/ Be sure to take a look at the diagrams shown on the above webpage. Good luck, Bruce Where did you set the stepper pins at? I started to do an experiment with my BBD, then got smashed up in a car accident and forgot I started it until I did a trip and realized I was only getting about 12 mpg with it. I was intentionally running the stepper pins in the full rich position like the 'Nutter' bypass says also to try and keep it rich so it 'might' burn that alcohol mix crap. It still won't burn the mixed sh.t. Anyway, I remembered about this experiment at the end of a trip and went back and adjusted the stepper pins to the middle of their travel like they would run with the stepper and O2 working perfect. This has the shoulder of the pin just sticking out from the back wall of the carb where the carbon stain is located from when the stepper worked. This radically boosted my high speed power back up and got my mileage back to over 20 mpg highway or close to 11L /100 km. Mike 86/00 CJ7 Laredo, 33x9.5 BFG Muds, 'glass nose to tail in '00 88 Cherokee 235 BFG AT's Canadian Off Road Trips Photos: Non members can still view! Jan/06 http://www.imagestation.com/album/pictures.html?id=2115147590 (More Off Road album links at bottom of the view page) > My vote is for the "stepper motor" enrichment system also! When > built, they were worried about NOX emissions caused by lean [quoted text clipped - 23 lines] > > Good luck, Bruce > My vote is for the "stepper motor" enrichment system also! When > built, they were worried about NOX emissions caused by lean [quoted text clipped - 23 lines] > > Good luck, Bruce This sounds like a solution. I will take advantage of it this weekend. It has to be better than the performance that I'm getting now. Thanks for your advice, Andy >> My vote is for the "stepper motor" enrichment system also! When >> built, they were worried about NOX emissions caused by lean [quoted text clipped - 27 lines] > It has to be better than the performance that I'm getting now. Thanks > for your advice, Andy Here is another link on that mod: http://home.sprynet.com/~dale02/ignmods.htm I have a couple comments about it. I always just run 2 new wires to connect the orange and purple wires at the ignition module to the distributor rather than mess around inside the harness. I disagree with John Nutter's carb setup. He states to put the stepper motor's 'air mix' pins into the full rich position or all the way into the carb. This basically doesn't work for high speed, it only works for idle and low speeds. I have found that setting the pins in the center of their travel where the O2 would have them gets the top speed mix right. This means rocking them with a small screwdriver until the shoulder of the pin is just clear of the back wall or removing the stepper and moving them by hand then putting it back on. The idle mix is controlled by two screws down front. You will love the power boost! A good 25% 'seat of the pants boost with at 'least' a 10 mph per gear increase. My 86 will top out at 4400 rpm now. 4th gear will bury the speedo and I have no urge to find out how fast 5th will go... I can also pass Canadian emissions with the BBD manually tuned. Not just mine but a lot of friend's rigs too. Mike 86/00 CJ7 Laredo, 33x9.5 BFG Muds, 'glass nose to tail in '00 88 Cherokee 235 BFG AT's Canadian Off Road Trips Photos: Non members can still view! Jan/06 http://www.imagestation.com/album/pictures.html?id=2115147590 (More Off Road album links at bottom of the view page) Mike is absolutely correct on not messing with the OEM wiring harness. I elected to splice in two new wires on the distributor side of the connector and take them to the Ignition Control Box and splice again on the Box side of those connectors. I would suggest you make those connections with SOLDER then seal them very well with some sort of insulation. Also, If you are ever interested in "un- doing" your work, a replacement control box and distributor module are all it takes. Also, I totally removed the "stepper motor metering rod" and blocked off those fuel passages and reinstalled the stepper motor housing to maintain appearances. After that, I retuned the BBD to correct the mixture. The Main Jet metering rods have enough adjustment to give you MORE than enough fuel. I started out with them at the richest setting and kept re-adjusting toward lean until I could detect the beginnings of a "surge" under a load, then went back a tiny bit richer which left it "spot on". Did the same thing with the accelerator pump, the factory specification of 1/2' below the carb top boss is too much of a squirt. With that setting, each time I floored the accelerator I would get a little puff of black smoke which indicated "too rich". I lowered the pump rod to about 5/8" below the boss and black puff went away! Experimentation is what it is all about. I am sure if I had a different transmissioin or tire size or differential gears that some of the settings would require minor tweaks. But to me that is a major part of the reason for owning a REAL Jeep instead of an imitation! Good Luck, Bruce > Mike is absolutely correct on not messing with the OEM wiring > harness. I elected to splice in two new wires on the distributor [quoted text clipped - 26 lines] > > Good Luck, Bruce Interesting.... Those pins are 'air' mix pins. I have been worried about running mine too lean and burning up pistons because I run on the highway lots. I now think I might play a little more with them to see what kind of mileage I can coax out of her. Originally I had them set to give me 23+ mpg. Now I think they are one notch richer than that because I seem to be just under 20 mpg or I need to tweak the vacuum piston (main jets) setting. There are two main jets inside the carb for high speed. These are adjustable for the top end mix I think. I tried running with them a bit rich also just to see if I could burn that alcohol mix crap, but all I did was drop the mileage even more, no performance increase. Are these the ones you are 'playing' with? I would almost think a tailpipe sniffer would be in order to get the main jets 'proper'. or lots of tweaking. Mike 86/00 CJ7 Laredo, 33x9.5 BFG Muds, 'glass nose to tail in '00 88 Cherokee 235 BFG AT's Canadian Off Road Trips Photos: Non members can still view! Jan/06 http://www.imagestation.com/album/pictures.html?id=2115147590 (More Off Road album links at bottom of the view page) Yup, the "Main Metering Rods" and the "Main Jets" that those rods operate inside of are your real choice for mixture adjustments. Being an "old geezer" that grew up tinkering with 60's and 70's Mopars, I have the advantage of knowing what a BBD is supposed to do BEFORE "uncle sammies EPA" screwed things up. The original BBDs did not have that stepper adjustment, and the passage that it opens and closes did not exist. Knowing that, I simply blocked them and returned my BBD to a late 1960's state of tune. I wish I could take you for a ride in my CJ, it amazes people! You can NOT "bump" the engine over with the starter because it starts instantly. It idles so smoothly, the only way you can tell it is running is listening. And I reverified this yesterday, you can run 20mph in high gear on flat ground and floor the accelerator resulting in a smooth speed up without any hesitation. I am not relating all of this to brag, just to convince folks that you CAN get the BBD to run just fine if you have the skills and time. To comment on your "tailpipe sniffer" idea, you already have part of it! Your exhaust pipe has an Oxygen Sensor port, and the performance industry sells a "mixture monitoring" system that will screw right in place of the stock O-Sensor. This allows you to observe the mixture while driving. Hot rodders use them to get the best air to fuel ratio, so can you! Hang in there! > Yup, the "Main Metering Rods" and the "Main Jets" that those rods > operate inside of are your real choice for mixture adjustments. [quoted text clipped - 22 lines] > > Hang in there! LOL! You are preaching to the converted! I love the BBD. My CJ7 runs as nice as you describe yours running 'and' passes Canadian emissions with decent numbers. It isn't a fluke either, I have tuned and 'Nuttered' quite a few with the same results and emissions passes. I have the manual choke setup and also get instant starts, even at -20. I have had many folks wonder what is in it for an engine when they (don't) hear it sputtering at idle and think it must be a V8 when they see me walk up sand pit walls. I set my idle mix up with a glass of beer sitting on the air filter and get no ripples.... :-) Unfortunately the emissions sniffer actually wants a slight lean rumble in it for the good numbers so I adjust it accordingly. (1/4 turn lean from 'best lean') It has passed it's last one due to age! Blocking those air passages to turn it back is a great idea if you are a serious tinkerer. I think I will stick with manually setting the pins for the best power unless I stumble across one of those tuning tools you mentioned. I wouldn't mind getting a normal BBD, some friends have managed to find them. I am running 3.31 gears with 33x9.5's and it just won't stall. I can walk up sand pit walls at 400 rpm and if I get too steep it just churns the tires into the sand. Same as pulling in high gear. I just find with my gearing, if I use 5th on the highway it lugs the engine at 1700 rpm or so. If I stay with 4th as a top gear which turns about 2300 rpm at 65 mph, I get the snap in the gas pedal and about 5 mpg more. 1st gear will light up my tires way too easy, 2nd tops out at 54 mph turning 4400 rpm, 3rd pulls fast to 72-75 mph, 4th buries the speedo and who knows for 5th... Mike 86/00 CJ7 Laredo, 33x9.5 BFG Muds, 'glass nose to tail in '00 88 Cherokee 235 BFG AT's Canadian Off Road Trips Photos: Non members can still view! Jan/06 http://www.imagestation.com/album/pictures.html?id=2115147590 (More Off Road album links at bottom of the view page) Sorry to rant on the BBD, but I have read SO many articles on how they suck and you should chunk 'em in the garbage and install a Weber, a Holley or swap to Injection. Anyone that knows how carbs actually work would not even consider a Weber and if you have been around as many Holleys as I have, you would rather walk than depend on one of those! I like injection, my 95 Cherokee runs great with it. However, my CJ runs just as good with it's modified BBD and I can absolutely be certain of REPAIRING the CJ and making it bring me home. Not so for the Cherokee with it's "Black Magic" control system! By the way, I have sent several buddies links to your photo postings. Those are great! Bruce from Texas On Feb 24, 12:09 pm, "Highcountry" <highcountry2...@hotmail.com> wrote: > Sorry to rant on the BBD, but I have read SO many articles on how they > suck and you should chunk 'em in the garbage and install a Weber, a [quoted text clipped - 12 lines] > > Bruce from Texas Agreed. This weekend I finally gave up on my Weber and reinstalled my Carter. Gas mileage, cold starts and throttle response have returned. I opted to keep my stepper motor/metering pins intact as my emissions test is coming up next month. I could almost breathe out of my exhaust pipe. Hey Mike: How do you adjust (and hold!) the stepper pin location if the stepper motor is jammed? >>> My vote is for the "stepper motor" enrichment system also! When >>> built, they were worried about NOX emissions caused by lean [quoted text clipped - 62 lines] > Jan/06 http://www.imagestation.com/album/pictures.html?id=2115147590 > (More Off Road album links at bottom of the view page) The pins move in steps. They rock. From the top I can be persistent with a mini screwdriver and get them to rock or I have taken off the stepper and made them move that way. Once 'moving', they seem to stay so the screwdriver can get it. Or I just plain got lucky with the screwdriver and it needs to be opened. I didn't have needle nose pliers needly enough to grab from the top. Mike > Hey Mike: > How do you adjust (and hold!) the stepper pin location if the stepper [quoted text clipped - 66 lines] >> Jan/06 http://www.imagestation.com/album/pictures.html?id=2115147590 >> (More Off Road album links at bottom of the view page) My pins are on the end of a "ball screw" that is attached to the stepper motor. Motor is jammed, I have no way of spinning it to make any adjustments. > The pins move in steps. They rock. From the top I can be persistent > with a mini screwdriver and get them to rock or I have taken off the [quoted text clipped - 75 lines] >>> Jan/06 http://www.imagestation.com/album/pictures.html?id=2115147590 >>> (More Off Road album links at bottom of the view page) I would be thinking about using something like JB Weld to fix them in place or if I had access to the tools to test mix I might think about pulling the pins and blocking the air passages like Bruce did. I am going to play with my pins a bit more as soon as it thaws or I do the next highway run to get camping so I can follow up where I have them set finally if you would like. Just FYI I have grabbed the stepper main shaft with small vise grips and rocked it in and out to free them up before. It moves in steps literally and can take some pushing or rocking in and out. Mike > My pins are on the end of a "ball screw" that is attached to the stepper > motor. Motor is jammed, I have no way of spinning it to make any [quoted text clipped - 82 lines] >>>> Jan/06 http://www.imagestation.com/album/pictures.html?id=2115147590 >>>> (More Off Road album links at bottom of the view page) |
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