85 gsl-se charcoal canister options
 

Does anyone know if there is an aftermarket compatible replacement for the stock charcoal canister? Are there any specifics to be aware of when looking? I see that the tank vent fitting is substantially reduced and I am assuming there may be a check valve of sorts within the inlet. The second line (to the oil filler tube) seems wide open with no resistance. Long story short, I was out driving one day and it was pretty hot. An hour into the drive I noticed the fuel pump really making some noise so I stopped for a moment to cool off. After starting up again, right away the car wanted to stall when applying the throttle. I turned it off, opened the fuel cap and a tremendous amount of pressure blew out. After sitting a few more minutes, I started again and drove for another 30 minutes, with no problems, and running as beautifully as before. As I was pulling into my driveway, I noticed the fuel pump start to get loud again and, once I parked it, I removed the cap again and there was pressure. This car does sit a lot but, aside from that, the whole system from tank to canister has been cleaned, refurbished and replaced as needed. The charcoal canister is the only thing untouched. I first looked at that, and right away, I noticed the tank vent inlet could not be blown through. Is this normal? Should there be some resistance? Left tank vent line disconnected, took it out yesterday for a ride and no pressure when removing gas cap at all. I've seen similar situations here on the forum but no one has seemed to provide a clear answer aside from eliminating the canister. Also, could the fuel tank vent line just be spliced in with a tee into the oil filler tube vent line and let it work out through the carbon that way?

Well, if you know how a charcoal canister works, the fuel vapor (*and oil vapor from the filler tube) is allowed to collect here when you shut the engine off. The next time you start the engine, a vacuum is pulled against the canister, sucking the fumes back into the intake to be burned. This prevents the vapor from getting to atmosphere - both keeping your garage smelling a lot better, and it's supposed to be better for the environment, too. Regardless, the main line going to the canister is larger to allow the relatively small vacuum tube to pull the vapor in. If that's clogged, you'll probably never know it.

You could be trying to diagnose several different symptoms at once; the fuel pump sounding funny followed by a lot of pressure built up inside the tank means that your return fuel line to the tank could be clogged. If that's the case, you're effectively deadheading a significant pressure source of fuel, and I doubt it'd run right with that much pressure behind it. One thing to check specific to the -SE is the Fuel Pressure Regulator which is vacuum operated at the back or front of the fuel rail. When vacuum is applied, as during heavy load, there's an internal shunt that closes down to increase fuel pressure through greater restriction on the return side. If that Regulator is bad, it could be engaging with little or no vacuum applied, which will result in high fuel pressure all the time. IIRC, the spec is something like 35psi at idle, and up to 50psi at WOT.

The other thing not to overlook is that it could be a bad fuel pump that's about to go out, or a clogged Fuel Injection Filter located back by the pump that most people never change. Have a look at those and report back,

[QUOTE=LongDuck;12288663]Well, if you know how a charcoal canister works, the fuel vapor (*and oil vapor from the filler tube) is allowed to collect here when you shut the engine off. The next time you start the engine, a vacuum is pulled against the canister, sucking the fumes back into the intake to be burned. This prevents the vapor from getting to atmosphere - both keeping your garage smelling a lot better, and it's supposed to be better for the environment, too. Regardless, the main line going to the canister is larger to allow the relatively small vacuum tube to pull the vapor in. If that's clogged, you'll probably never know it.

You could be trying to diagnose several different symptoms at once; the fuel pump sounding funny followed by a lot of pressure built up inside the tank means that your return fuel line to the tank could be clogged. If that's the case, you're effectively deadheading a significant pressure source of fuel, and I doubt it'd run right with that much pressure behind it. One thing to check specific to the -SE is the Fuel Pressure Regulator which is vacuum operated at the back or front of the fuel rail. When vacuum is applied, as during heavy load, there's an internal shunt that closes down to increase fuel pressure through greater restriction on the return side. If that Regulator is bad, it could be engaging with little or no vacuum applied, which will result in high fuel pressure all the time. IIRC, the spec is something like 35psi at idle, and up to 50psi at WOT.

The other thing not to overlook is that it could be a bad fuel pump that's about to go out, or a clogged Fuel Injection Filter located back by the pump that most people never change. Have a look at those and report back,



Thanks for the info. If there was a clogged canister, and the tank could not vent, wouldn't that build pressure? Secondly, this"fuel injection filter" (assuming you are not talking about the main inline filter) I've heard spoken of before near the fuel pump, my car does not have. I'll reiterate, I've been through this system thoroughly during the resto and all lines, tank, pickup in tank have been thoroughly cleaned and or replaced. I even pulled the cut/check valve over tank and cleaned and tested that. Fuel pressure regulator (I believe was under the intake on top of the motor) , fuel pump were pressure tested but not replaced so I will keep those in mind. I'm not second guessing your input because it may be right. I just like to start simple and work my way into difficult. Right now I do know that disconnecting the canister solved the problem but more driving will be required to satisfy my theory. My question to you is: are you saying that by disconnecting the canister, I, in fact, solved nothing?

I didn't think that canister would cause this issue because it is not a close canister. Doesn't it have a hole on the bottom?

Yes but it does no good if you cant get past the inlet tube.

One way to test if it is the issue is to just remove/disconnect the lines.

Thanks, yes, that's where this thread begins.

I have never seen an aftermarket charcoal canister on an SA or FB. Not even on an FC. I've seen people install the nice plastic FC charcoal canisters on an SA or FB however. I have a good amount of pressure in my 85 that I installed an SE engine into. When I remove the gas cap there is a good amount of pressure. It has always been this way on every 7 that I've had and have never had an issued with tank pressure causing issues.

Can someone confirm (on a known working canister) whether or not when blowing through the fuel tank vent port on the canister if you can feel air come out the hole on the bottom of the canister? I can with the larger port (oil filler vent hose) but the fuel vent side I can not.

I'll check for you today and report back.

Well, I don't know how to check for a "known working canister," but on my '84 SE (51K miles) my canister works the same as yours: when I blow through the larger oil filler vent line, I feel air come out the hole on the bottom of the canister, but when blowing through the fuel tank line I don't. Further, blowing through the oil filler line is very easy, as if there is very little restriction; blowing through the fuel line is very difficult, although some air is flowing very slowly. Sucking on the fuel vent line is somewhat less difficult. Fully blocking the oil filler vent line nipple or not when I did these tests made no difference.

All this comes with a caveat: I have been experiencing the same fuel tank pressure, fuel pump whine and stalling symptoms you describe, but only in very hot weather (90 degrees plus). Maybe we both have the same issue(s)?

Alright, a couple of things stand out from your replies above, so I'd like to take them in order;

1) Fuel Filter - There's a hard metal Fuel Filter (not plastic, as it wouldn't sustain the pressure of FI) located right near the fuel pump, but it's separate from the pump. This Filter is about 8" long and includes several metal line fittings that feed into the pump. If your car doesn't have this filter, it may have been bypassed - or it does, and maybe I misunderstood your description. Regardless, it should be there, and is about $80 to replace, which is why most people don't replace them on a routine basis - as typically, they don't cause problems unless you get something horrible in the tank (sugar/dirt/sand/etc.).

2) Charcoal Canister Function - What you describe for the function of the 2 lines leading to your Charcoal Canister sound correct to me. The big line going to the oil filler neck is to suck out any water or oil vapor from the case during engine operation, and also serves to prevent 'Lung Butter' which is a white buttery substance that's a mix of oil and water that accumulates near the oil fill neck or the inside of your oil fill cap when your lines to your Charcoal Canister are NOT working (*or there's no vacuum line to your Charcoal Canister). That's usually the first sign that the CC is bad = lung butter in the filler tube. Point being, if you have the small line connected to a vacuum source at the intake plenum, and the big line attached to where it belongs on the oil filler neck, you're golden. However, there is no Fuel System connection to the CC to my knowledge. You need a little pressure on the air space and fuel volume in the fuel tank to help the pump, which leads to...

3) Fuel Tank Pressure - It's normal on an -SE to remove the gas cap and have pressure release. Usually, it's just a bit of vapor in a 'pfffffftttt' that comes out - not a 'whoosh', and certainly not spitting liquid fuel out of the tank opening. Underneath the car, there's a 1/4"ID low-pressure fuel hose that goes from the top of the tank connections over to a metal cap spot welded to the body of the vehicle. This rubber hose just sticks into a hole in the side of that metal cap and serves as the vent. There may have been a sponge inside the cap, but I've never pulled one off, so I'm not sure. Regardless, that vent hose is connected to the roll-over junction which shuts off fuel flow to the pump if the car is upside down, and is a safety feature.

Maybe someone can shed some light on the Charcoal Canister connecting to the Fuel System that I'm overlooking, but as your symptoms describe, if you're getting stalling during 90degF weather, that's unusual and could be a Fuel Pump going bad (or clogged Filter). I've been DD my -SE in 115-118F without any problems these last few weeks, and have been doing that for years in much higher temps.

1) Fuel Filter - There's a hard metal Fuel Filter (not plastic, as it wouldn't sustain the pressure of FI) located right near the fuel pump, but it's separate from the pump. This Filter is about 8" long and includes several metal line fittings that feed into the pump. If your car doesn't have this filter, it may have been bypassed - or it does, and maybe I misunderstood your description. Regardless, it should be there, and is about $80 to replace, which is why most people don't replace them on a routine basis - as typically, they don't cause problems unless you get something horrible in the tank (sugar/dirt/sand/etc.).

Yes, that is the main inline filter I was referring to. I have that. Is this what you meant by "clogged fuel injection filter"? The filter I was eluding to was one on the fuel pump. I've read where some people clean and check these. I have no such thing on mine.

2) Charcoal Canister Function - What you describe for the function of the 2 lines leading to your Charcoal Canister sound correct to me. The big line going to the oil filler neck is to suck out any water or oil vapor from the case during engine operation, and also serves to prevent 'Lung Butter' which is a white buttery substance that's a mix of oil and water that accumulates near the oil fill neck or the inside of your oil fill cap when your lines to your Charcoal Canister are NOT working (*or there's no vacuum line to your Charcoal Canister). That's usually the first sign that the CC is bad = lung butter in the filler tube. Point being, if you have the small line connected to a vacuum source at the intake plenum, and the big line attached to where it belongs on the oil filler neck, you're golden. However, there is no Fuel System connection to the CC to my knowledge. You need a little pressure on the air space and fuel volume in the fuel tank to help the pump, which leads to...

You say the small line on the canister is connected to a vacuum source on the plenum. See service manual 4B-2. Small line clearly goes back to the tank via the cut/check valve. It makes no other stops along the way. Disconnecting this from the canister fixes all my issues. Therefore I have concluded that my canister is clogged. Am i missing something?

3) Fuel Tank Pressure - It's normal on an -SE to remove the gas cap and have pressure release. Usually, it's just a bit of vapor in a 'pfffffftttt' that comes out - not a 'whoosh', and certainly not spitting liquid fuel out of the tank opening. Underneath the car, there's a 1/4"ID low-pressure fuel hose that goes from the top of the tank connections over to a metal cap spot welded to the body of the vehicle. This rubber hose just sticks into a hole in the side of that metal cap and serves as the vent. There may have been a sponge inside the cap, but I've never pulled one off, so I'm not sure. Regardless, that vent hose is connected to the roll-over junction which shuts off fuel flow to the pump if the car is upside down, and is a safety feature.

I agree and now I see why. The fuel vent inlet on the canister has a significantly reduced orifice for the vent line from the tank. This will indeed cause the vapors to back up a bit and find the easiest source of exit, which at times, will be the gas cap. My understanding of the system is that vapors are sent to the canister through the smaller hose and pulled through into the canister by the larger hose, by vacuum, into the filler neck to be sucked into the motor for burning. The carbon in this canister mainly acts as a catalyst to mask odors while vehicle is not running. Having it apart I see that the two inlets just sit above a foam media followed by the bed of carbon. Outside air can be pulled in from the hole at bottom through the carbon and filter media while the motor is running and sucked back into the motor through the larger tube. Think of it as a closed loop that runs off vacuum from motor. When shut off, vapors from motor and tank are allowed to run free inside and vent to atmosphere through the carbon bed. Upon startup, the loop re-initiates and all the vapors are sucked in and burned through motor.

Maybe someone can shed some light on the Charcoal Canister connecting to the Fuel System that I'm overlooking, but as your symptoms describe, if you're getting stalling during 90degF weather, that's unusual and could be a Fuel Pump going bad (or clogged Filter). I've been DD my -SE in 115-118F without any problems these last few weeks, and have been doing that for years in much higher temps.

Car runs beautifully with the vent line disconnected from canister. I am rebuilding canister and will report whether or not issues remain. Thanks again for the input.

Can the canister be opened and repacked with charcoal?

I can confirm that the small line does go uninterrupted from the charcoal canister to the fuel cut-off valve next to the driver's rear wheel; see the attached picture.

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Fuel cut-off valve near the driver's rear wheel. The line highlighted in red goes forward to the charcoal canister in the engine bay.

slvrghst, I'll be interested to hear whether or not you are successful in rebuilding the canister.

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Yes with a cut off wheel on a die grinder.

I will attach a pic when I get it all put back together along with sources to all necessary parts.

Let me note that the foam pads are pinched into the metal strainers. In one pic you see them separated. To do this, I had to trim them around edges with razor blade. The cleaner one is the one on top and thinking back could probably have been reused. The clogged black one is from the bottom. Not to confident that one could have been cleaned thoroughly but its out and I'm changing it.

Let me also note that the top filter seems to have a paper film possibly to keep the carbon from being sucked through the foam and into the motor. If you attempt this repair, try your best to preserve this top filter because it will be nearly impossible to duplicate. Lesson learned but I am pretty confident that I will find a remedy and I will pass that along as well.

It looks to me but would Aeropress filters work? They look a little small in diameter, so could coffee filters be a suitable replacement?

Parts I found that will do the trick:

Napa Vent Filter part# 2998 $3

22oz container carbon from local pet smart $7 (used ¾ of it)

Quicksteel bonding agent $8

Small Zip ties

1 coffee filter

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Here is a step by step how to for those of you wanting to rebuild your old clogged canister. There are many how to videos on you tube so this will be redundant. This is however the one and only (or so I’ve found) one dedicated to our particular canisters.


As you will see these units are sealed and are not meant to be serviced. To get around this I used a die grinder with a cutoff wheel and, following the seam at the top of the canister, I cut the top off.
(TIP!!!! Make sure to find the sweet spot. What I mean is that if you cut too close to the seam you will cut into the lid. Cut too low you will cut into the metal strainers. Make a test cut about 1/8” down from lid and make sure it goes through with no obstruction. Once you find the sweet spot proceed with the cut). In the photo below notice top right corner of strainer where I accidentally cut into it while cutting top.

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Empty contents, examine filters on the metal strainers. The one to be concerned with is the bottom. The top has a yellow paper element and is probably fine so check it and leave it alone if possible. The bottom on mine was pretty caked with carbon and debris. If cleaning does not work, remove the filter media with razor blade following the inside edge of the metal strainer and proceed with the next step. If cleaning was enough proceed to reassembly.


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The Napa vent filter is thicker than the filter element that came on the canister originally so what I did was split it in two. Just find an edge that is coming apart and pull it apart. It’s very simple. A razor blade or exacto knife can help too if needed. (In other words think of a pancake on a plate, and taking a knife start at one end and slice horizontally across the pancake until there are two.) Next, using the metal strainers from the canisters as guides cut out material needed to fit strainer (filter pieces are a bit larger diameter than what is needed). Once you have your pieces trimmed to your liking you are ready to adhere to ring. Originally the foam was pinched in the ring to keep it in place. This cannot be done with destroying the ring so I found using small zip ties in strategic places help to keep it secured to the strainer. As an added security I ran a little super glue along the outer edges to keep it from rolling back and possibly allowing carbon by. If you decide to change the top, use the same steps but you will have to duplicate the paper element that comes with it originally. To do this I cut out the needed diameter out of a coffee filter and sandwiched it in between the filter media and strainer.

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Once all the strainer filters are reconstructed, canister thoroughly cleaned you can now reassemble. Make sure when installing the strainers that the filter media is facing the carbon. Install the bottom strainer and pour in carbon.
(TIP!!!! Check dust content of carbon before installing. Using a sifter or strainer of sorts use a little compressed air and blow through it to remove any dust. I do not recommend rinsing with water unless you can thoroughly dry it.)
As you fill, tap the container on bench to settle the carbon and compact it as much as possible. Occasionally check with top strainer and lid so to not overfill but make sure it’s enough so that when it’s back together there is no slack inside. You should be able to shake it with no internal rattles.

To install the lid, I sanded area to be bonded, matched the lid up to where it exactly came off (pre-mark before cutting if this helps). Using a clamp, I secured the lid and using the Quicksteel I formed a putty weld all around the cut seam and let cure overnight. You can stop here if aesthetics are of no concern to you.


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After the putty cured, I sanded down smooth, primed, water sanded (repeat until desired effect or use bondo) and painted the entire canister.

IF ALL GOES WELL FINAL PAINTING WILL BE DONE THIS WEEKEND AND I WILL ATTACH PICS OF FINISHED PRODUCT....STAY TUNED

Nice work!

Very nice. Thank you, sir.

Wanted to add these to last post but wouldn't let me edit. Anyways, here are the final pics. I will update you guys after it is installed on car and tested.




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Just for your viewing pleasure, here is what it will be going back on.

Thanks for reading guys, I hope this helps those of you in the same situation. I will post my results on whether or not this solved the issues but it may be a while. This is not my daily driver.


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We'll be needing an extensive photo album of that beautiful car.