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Thread: Charcoal canister

  1. #1
    Fuel Injected! JeepsAndGuns's Avatar
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    Charcoal canister

    Just a tiny bit of a back story to understand why I am asking about this.
    When I bought my 79 cherokee, it had caught on fire under the hood. The trans was pukeing atf out the fill tube onto the exhaust and then caught fire. It burnt the whole right side of the engine and compartment. Thats why I got it so cheap. It burnt all the wiring, heater hoses, heater box, ac hoses, spark plug wires, air cleaner, carb, battery, and charcoal canister before they got it out.
    I replaced all damaged parts (includeing the trans, witch I swapped in a 4 speed) except for the ac lines and the charcoal canister. The ac unit inside the jeep was all messed up anyways, so I simply removed everything except the pump (kept it for OBA) The charcoal canister I never replaced because back then, I didnt even really know what it did. I just knew it was for emissions, and figured I didnt need it.
    Fast forward to now and I have been meaning to put one back in for a while now, but its just never been high on my list. But while checking the oil after driving it last weekend I kept smelling gas. I was checking all my fuel lines and hoses and all were good, no leaks. Then I remembered the fuel tank vent hose, yep, theres the gas smell. SO I figure I need to take care of this, not so much for the smell and emmissions, but for saftey, as it just venting fumes into the engine compartment! How or why, did I not notice this untill now!


    The canister on my wrangler simply has a little vaccume valve, and when it gets vac (when engine runs) it opens and vapor is vented into the air intake tube before it goes into the TB. So I started to look for one of these, untill I remembered all the parameters for CCP in my bin files on my fuel injection.
    SO, I was thinking would there be any reason not to just get a compatable canister/valve and just hook it up and run it and let the ecm controll it? And if so, would there be any reasons to alter the ccp settings in the bin from stock? I'm thinking no?

    And last, I was thinking about heading down to the pull a part this weekend, so what vehicles could I look for to get a compatable canister other than (I assume) the tbi trucks? And where would it be located on them? I have never paid attention to the canister on them while pulling parts, so I have no clue.
    79 Jeep Cherokee, AMC 401, T-18 manual trans, hydroboost, 16197427 MPFI system---the toy

    93 Jeep YJ Wrangler, 4.0L, 5 speed, 8.8 rear, homebrew hub conversion and big brakes, hydroboost, 2.5in OME lift, 31x10.50's---the daily driver

    99 Jeep WJ Grand Cherokee limited, 4.0L, auto, 2wd, leather and power everything, 99% stock---the long distance highway ride.

  2. #2
    Super Moderator dave w's Avatar
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    Most GM vehicles have the charcoal canister on the left side of the engine compartment, just behind the radiator support. Sometimes a large lift cam will need changes to the CCP parameters. Generally, 1987 ~ 1995 Pickups, Suburbans, Blazers and even the S10 vehicles use an almost identical Charcoal Canister. I live in Washington State, so I have to be careful to avoid the California Emission Charcoal Canisters.

    dave w

  3. #3
    The charcoal canister recommended on the IFSJA board is a drop in replacement. And since you no longer have the carb vent hose, you don't have to drill out the second port. Around $40 IIRC. Add your CCP valve and you should be set!
    Familiar with 1227747 and 16197427 PCMs

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    the only change you might need to think about is if the solenoid is normally opened or normally closed.

    for GM stuff, most of the early units i've seen are normally open, then transition to normally closed.

    all of the masks i play with have an option to choose between them, but if yours doesn't, you'll either need to make certain the one you grab will work or patch code.
    1995 Chevrolet Monte Carlo LS 3100 + 4T60E


  5. #5
    Fuel Injected! JeepsAndGuns's Avatar
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    Robert, I am using a 7427, so if I grab the canister from a truck/van with the 7427, I would assume it would work fine? Any idea if one from a 7747 would work too?

    FSJ, are you talking about like a new replacement one? When I removed it I removed the mounts and all and trashed it, the area it was in is now taken up by relays and a wiring junction, so I may have to find a new location for it.
    79 Jeep Cherokee, AMC 401, T-18 manual trans, hydroboost, 16197427 MPFI system---the toy

    93 Jeep YJ Wrangler, 4.0L, 5 speed, 8.8 rear, homebrew hub conversion and big brakes, hydroboost, 2.5in OME lift, 31x10.50's---the daily driver

    99 Jeep WJ Grand Cherokee limited, 4.0L, auto, 2wd, leather and power everything, 99% stock---the long distance highway ride.

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    i would play it safe and use one from a 7427(maybe check out the XDF for whatever mask you'll run to see if NO and NC are supported?). while one from a 7747 controlled vehicle might work, i personally have no way of verifying this.
    1995 Chevrolet Monte Carlo LS 3100 + 4T60E


  7. #7
    Fuel Injected! gregs78cam's Avatar
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    The OBDII cars, vans and pickups I think have the canister, and solenoid mounted to the fuel tank. They are a nice rectangular unit that I believe is more compact than the usual big round ones.
    1978 Camaro Type LT, 383, Dual TBI, '7427, 4L80E
    1981 Camaro Z-28 Clone, T-Tops, 350/TH350
    1981 Camaro Berlinetta, V-6, 3spd
    1974 Chevy/GMC Truck, '90 TBI 350, '7427, TH350, NP203, 6" lift, 35s

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    Fuel Injected! pmkls1's Avatar
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    I think that this thread is already past this point, but I would definitely be finding/installing a functioning charcoal can and preferrably a GM electrically controlled unit so that you can have complete control over it. I ran into a similar problem way back in the day when I was young and uneducated. The resulting experience I will share in a minute. First, though, after looking at the 427 schematics on here it appears that the purge valve operates the same as on my car even down to the wire colors. The solenoid is in a normally closed state and receives b+ voltage with the key in the run position from a shared fuse. The ecm then grounds the solenoid opening the valve when it is commanded on. Going solely on this info and GM's typical school of thought, I would think that most cans of that era are probably similar with many sharing the same part number giving you a pretty large pool of vehicles to rob from. As was stated earlier, most can be found in the left side of the engine compartment near the front. The size is fairly compact and cylindrical shaped being approximately 4" in diameter and maybe 6-8" tall and the solenoid is mounted directly on top with a red 2-wire connector.

    On to the story, which happened many moons ago and there was a specific chain of events that led to the final result. Back then I was a carb and HEI guy and ripped out anything that I didn't think was necessary. I had purchased an '87 T/A that originally had the computer controlled quadrajet and was naturally plagued with driveability issues. So, out with the carb and small cap dizzy and in with a Carter AFB and a stand-alone 4-pin HEI dizzy. I left the charcoal can in but the outlet line to the engine was disconnected along with any vacuum line I felt was unnecessary. I drove the car this way for a few years making minor changes along the way including the installation of a wieand stealth intake, a holley 600 cfm vacuum secondary carb, and a functional snorkel style hood scoop. Well, early on I quickly noticed an audible low-pitch hum when standing near the car with the engine shut off, for example after exiting the car or when approaching it. I eventually traced it to the can and eventually realized that this only happened in higher temps and was caused by fuel tank pressure forcing vapors out past the valve and of course the strong raw fuel odor was present as well. I also had to remove the gas cap slowly due to the hissing from the pressure in the tank and an occasional fuel mist out of the filler neck if there was still enough fuel remaining. The pressure buildup eventually led to issues where the pressure in the fuel system led to slightly higher pressures out of the fuel pump that the Holley could not handle and apparently the Carter had been able to (in subsequent projects I have experienced similar issues with holley carbs but quickly installed a carb specific fpr and alleviated the problem). It quickly led to problems with the float bowls overfilling and flooding the engine, especially after the car sat in the summer sun for a while. Not knowing why I was having problems, I would readjust the float levels and would temporarily the problem would go away but is was really because I had relieved the fuel system pressure by burning and spilling a lot of fuel in a short period of time. One day on the way to work the floats were stuck and the car was flooding badly, but I only had to make it 2 miles so I just limped it along. I was actually stopped by a highway patrolman due to the plumes of black smoke bellowing out of the exhaust as I nursed it along. He wrote me a warning for the smoke and my illegal window tint and was gonna let me continue on my way. But the car would not restart, however, so I got the rollback from work and pulled it in. Later that night I pulled the plugs out in the parking lot and cleaned them because I knew they were fouled. I reinstalled them and started the car so that I could drive it into the shop and fix it inside. Well, the engine did start but had about 2 dead cylinders due to the flooding and was shaking prety good.. I eased on the throttle and brought the RPM's up thinking that I could clear the fuel out enough to get the engine to smooth out. Well, as I eased it up to about 2500 RPM's the engine sounded like it was clearing up and then BOOM ! The engine backfired with an intensity that I can only compare to a good nitrous backfire on a drag car. Flames instantly shot out of the hood scoop and also into the passenger compartment somehow through the HVAC case. In no time people came running out of the shop with fire extinguishers as I instinctively shut down the engine (I think it was still running somehow but was too stunned to remember) It took somewhere along the lines of 6 extinguishers to put out the fire completely. As I stood there in shock I slowly began to survey the damage and piece together what just happened. Apparently a couple of cylinders had filled with a significant amount of fuel having a twofold effect. The first by allowing gas to seep past the rings into the crankcase as it sat for over 8 hours and apparently a lot of fuel made it's way in there. The second effect was it also kept fouling the spark plugs causing a misfire. At some point the raw fuel remaining in one of the cylinders ignited and exploded with enough force to shatter a rod and send shrapnel through the oil pan and consequently ignite the gas/oil mixture in the crankcase as it spilled out onto the pavement below. This also caused a large backfire out of the intake at the same time splashing burning fuel all over the top of the engine. The fire was put out fast enough that not much in the engine compartment was ruined luckily. Other than the literally "grenaded" engine, the worst damage was confined to the paint on the hood and tops of the fenders and the hood scoop. The explosion was pretty violent, though, causing a shockwave strong enough that the windows and floor of the second story showroom shook pretty bad. In fact, they shook so badly that a couple of the salesmen immediately called 911 before running out to see what happened expecting to find the shop on fire. They actually thought that something had exploded inside the shop, which was located under the showroom and my car was parked outside behind the building. I wish that I could admit to embellishing a little, but I'm really not. In fact, between causing such a stir in the showroom and being responsible for the fire department being dispatched, and emptying so many fire extinguishers, I nearly lost my job. Anyhow, this would be an incredibly rare and extreme example of the possible consequences of improper or the complete absence of gas tank ventilation. But, there are just too many sources of ignition under the hood for me to be comfortable with the significant presence of fuel vapors and an open path to the tank.

  9. #9
    Fuel Injected! JeepsAndGuns's Avatar
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    Very interesting story, and makes a good point too!
    I removed the charcoal can because it was 1: burnt and damaged from the fire, and 2: I was younger and dumber and didnt really understand what it did and thought I didnt need it. I bought this jeep in 03, so I have been lucky for 9 years, but I no longer want to test my luck.
    I think the main reason I never noticed it untill now, was because 99.9% of the time I do anything under the hood, its when the engine is cold. When I checked the oil in it the other day I had just got done driving it, so the fuel had been sloshing around in the tank, and it was about the high 80's-low 90's. So it was making plenty of vapor.
    I am actually getting ready to go to the junkyard as we speak.

    Reading your story, do you think after you car wouldnt start, and it sat, that the tank pressure pushed fuel past the floats and was pouring fuel into the engine through the carb the whole time it sat? I am kinda surprised that if there was that much fuel in the cylinders that it didnt hydrolock it. I get mowers into the shop where the floats have stuck and filled the cylinder with gas, pulling on the pull cord it like trying to pull a brick wall. Or if electric start, before I suspect a bad starter, I always pull the plugs and try cranking again, sometimes I get a stream of gas out the hole!
    79 Jeep Cherokee, AMC 401, T-18 manual trans, hydroboost, 16197427 MPFI system---the toy

    93 Jeep YJ Wrangler, 4.0L, 5 speed, 8.8 rear, homebrew hub conversion and big brakes, hydroboost, 2.5in OME lift, 31x10.50's---the daily driver

    99 Jeep WJ Grand Cherokee limited, 4.0L, auto, 2wd, leather and power everything, 99% stock---the long distance highway ride.

  10. #10
    RIP EagleMark's Avatar
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    Charcoal Canisters are a good thing for the environment and do nothing to hurt performance. During purge they can effect AFR when doing a performance engine tune. On Off Roaders they are actually a safety factor.

    But if you must disconnect or remove them, install a vented gas cap and properly plug all lines at tank to avoid fuel leaks. Carbureted CC are way worse safety issue as there is no valve to control flow, well if you have all the vacuum lines and switches there is some control, but no back flow of fuel if you have a full tank and parked on an angle that fuel is covering the vent, then fuel flows down line and starts dripping out the canister...

    This isn't the first time and intelligent tech has shared a story of potential disaster or injury with us. I'm glad you did! It lets us all now how fast things can go bad from simple mistakes. We play with gasoline on a daily basis and forget the consequences if it is not done correctly! Just look at cell phones or static electricity during a fuel up videos...

    1990 Chevy Suburban 5.7L Auto ECM 1227747 $42!
    1998 Chevy Silverado 5.7L Vortec 0411 Swap to RoadRunner!
    -= =-

  11. #11
    Fuel Injected! pmkls1's Avatar
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    I do suspect that fuel was at least dripping into the intake while the car sat, but will never know for sure. Regarding the hydrolock comment, I THINK that I remember the engine having an issue cranking that I just disregarded at the time, but this was 11 or 12 years ago so my memory is pretty pretty faded by now. At that time I too simply didn't really understand the purpose of a charcoal can and in an attempt at eliminating the seeming miles of vacuum lines that were on the car from the factory I left it unhooked. There's no need to explain the absence of a charcoal can to me. I'm definitely not going to pass judgement on anyone for making a mistake due to a simple lack of knowledge and/or experience as I have made my fair share that sometimes resulted in quite a spectacular and/or expensive accident or failure of some type. In an unususally odd instance of coincidence I recently discovered that my ECM was not operating properly and one of the inoperative functions was the CCP ground circuit inside the ecm. For a number of reasons, I decided to quickly devise a temporary method of operating the CCP solenoid until I change ECM's. That and this thread brought back memories of my old T/A and I couldn't resist sharing my story. As far as the ccp tables in your bin, I would take a peek at them but with your setup I see no need to modify the settings. I would, however, perform a drive or two with the laptop monitoring things to verify it is functioning as intended. I would then only modify the ccp settings if you experience an issue that may be unforseen due to the fuel system design of your jeep although that is probably unlikely to happen.
    Nowadays, I obviously understand the purpose of charcoal cans and also hold a very different view and not just due to that incident. I like to think that besides keeping polluting gas vapors out of the atmosphere they also improve fuel efficiency by recovering those vapors and burning them through the engine. I know that the difference is probably not even measurable, but it at least makes me feel better. The charcoal canister is one of a few devices originally implemented for emmissions purposes that I don't have a personal issue with and will go out of my way to keep functional instead of remove on my own vehicles. Anyhow, good luck and let us know how things work out.

    Phil

  12. #12
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    the fuel economy difference is minimal.

    i use mine almost entirely for scent control.

    "what's that smell?"
    "the need to increase my CCP DC"
    1995 Chevrolet Monte Carlo LS 3100 + 4T60E


  13. #13
    Fuel Injected! JeepsAndGuns's Avatar
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    Well I went looking through the junkyard this morning and was starting to think I wasnt gonna find one. I was checking every late 80's up to mid 90's truck and suv. All the 7747 era trucks I found, all had the canister mounted to the drivers side of the rad support. They all also had 2 lines, one from tank, and the other to the TB? No type of valve or switch anywhere controlling them. I even looked at a few vans, all the same. No type of ccp valve or anything, they just went straight from the can to one of the front ports on the TB. (I think one of the ported ports?) All the 94-95 trucks/etc had already been stripped clean. I was down to the last row and about halfway through it and found a 95 burb, still had the engine, 350. Had the canister and followed the line and finally, it had a ccp vale on a bracket bolted to the t-stat housing. So I grab it, a few inches of the wires (the rest of the harness had already been hacked, or I would have got the whole harness) got the vac line and the canister/mount. I went ahead and looked, it still had the pcm, so since it was a V8, I went ahead and grabed it too. Never hurts to have a spare.

    Got home and started looking for a spot to mount it, this canister is not the smallest thing in the world at around 9.5 in tall and 5 in round. I am having a hard time finding somewhere to mount the thing! I thought I had more space under my hood, but I dont!...lol. About the only spot I have been able to fit it, is on the drivers side of the rad support, between the fan shroud and inner fender, and under my air filter. However I have a power steering line wanting to use that location too, but I may be able to do a little bending and moving of the line. I will have to try later, as I ran out of time today.
    Question, do these have to be mounted upright, or could it be mounted on its side? Or does anyone know of a more compact canister, mabey a little shorter? I kinda had slim pickings at the yard today.
    I hooked my vac hand vac pump/guage to the ccp valve and it holds vac, hooked up power and it opend and closed just fine, so atleast thats good.
    79 Jeep Cherokee, AMC 401, T-18 manual trans, hydroboost, 16197427 MPFI system---the toy

    93 Jeep YJ Wrangler, 4.0L, 5 speed, 8.8 rear, homebrew hub conversion and big brakes, hydroboost, 2.5in OME lift, 31x10.50's---the daily driver

    99 Jeep WJ Grand Cherokee limited, 4.0L, auto, 2wd, leather and power everything, 99% stock---the long distance highway ride.

  14. #14
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    FWIW: all of the W-bodies and probably a lot of other FWD cars, have the cannister mounted near the tank. ours specifically is right near the fuel filler neck. i'm not sure of the size off-hand, but it SOUNDS smaller than the one you have now.
    1995 Chevrolet Monte Carlo LS 3100 + 4T60E


  15. #15
    Fuel Injected! JeepsAndGuns's Avatar
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    Gonna try and fiddle around with it some this afternoon after work. If I have no luck finding somewhere for it to fit, I will look for other/smaller options.
    79 Jeep Cherokee, AMC 401, T-18 manual trans, hydroboost, 16197427 MPFI system---the toy

    93 Jeep YJ Wrangler, 4.0L, 5 speed, 8.8 rear, homebrew hub conversion and big brakes, hydroboost, 2.5in OME lift, 31x10.50's---the daily driver

    99 Jeep WJ Grand Cherokee limited, 4.0L, auto, 2wd, leather and power everything, 99% stock---the long distance highway ride.

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