Prototyping a Serviceable Charcoal Canister for the 40-Series

[procomsignathid]

Hey All! So far the fuel evap separators have been a success, so I'm thinking about adding another product to the lineup. I've been doing a lot of research on charcoal canisters, and I'm working on a prototype.

In my mind, this product is more like 3 that work together:

• A universal-fit charcoal canister designed to be serviced (such that you can open it, clean it out, replace the activated charcoal pellets if ever needed, etc.). A lifetime, non-disposable part. Similar to the evap separators, I'm planning to reinforce the port bosses and use Brass or SS NPT fittings
• Replacement brackets that bolt to the stock mounting locations (and potentially to other locations that are more preferable). I think I can build brackets that would work for both the OEM and new universal-fit canisters if I think it through (more on that later).
• Purge valve options:
  • A "simple" option, likely similar to the Redline kit (a vacuum-actuated valve), but with a restrictor on the purge outlet to reduce how much the canister purges at high-vacuum (this option purges at idle when the vacuum is highest, and when the engine is cold, neither of which is great, but its simple and it works). This option would be great for folks like me who have a de-smogged rig, and don't know (or care) if their emissions computer is working
  • An "optimal" option: A 12v solenoid valve on the purge outlet with some additional components to activate it when vacuum is in a sweet spot (gentle cruise) and the engine has had time to warm up. This would need a 12v lead from the ignition circuit (tied into the fuel cutoff solenoid or the feed to the coil). This option would be for folks who are super opinionated about air fuel mixture but also don't have an emissions computer (or their truck predates that stuff)
  • A stock "plugin" option that uses the same connector as the late-model 40s that have canisters with the purge solenoid wired into the emissions computer

Here's where I need some help: I am trying to source old charcoal canisters and brackets (I have one late-model unit on order, 77740-60014) so I can confirm dimensions. If you have any brackets or canisters laying around (the latter of which, if the part number is visible that is extra helpful), I would love to borrow them (and am happy to pay for shipping in both directions). The more I learn about canister/bracket dimensions, the better chance I have at making something that will work for all our rigs. Any help is appreciated!

I'm also curious if folks are interested in something like this, or if this seems like a fools errand. I thought it would be a good idea to check in before I got too crazy... Unlike the evap separators, this would be entering a market that already has a solution (the Redline kit is still available and I am one of their customers for this kit). Overall, I want something that is serviceable and a nicer/more-stable bracket setup. As I have learned more about the evap system (and because I generally cant help myself), I want to tinker with a better purge setup as well.

Anyways, thought I'd toss that out there!

 

[charliemeyer007]

Perhaps you should do a poll and see what the market is. Do most folks just cap the lines or kluge in something. I know if I had a gas smell in the cab I would want to do something about it.

As a side note, have you considered making other parts. The cab light lens on the B pilar or the cover for the upper mounted windshield wiper switch (both of those have been done and I think the program is downloadable as a 3d file some where around here.

Maybe some of the NLA switches could be done.

I need to decide soon if I want to try the 3D game before they regulate printers.

 

[procomsignathid]

I have considered some other products, especially the B-pillar light. I was thinking about making what I did in this post into a kit, to the point where I have purchased some bits and bobs to see what I can do. this is one of those cases where the plastic pieces are the easy part, I will need to find a mfr who can produce small qtys of nickle-plated spring steel and find the right rivet technology to reproduce it in a non-janky way. For the earlier-model 40s I think it would be great to use the same methodology with the appropriate style light.

I'm also looking into SLS and MJF printing, which would mean finding a US-based shop that has that equipment (usually in the 10s of thousands), and working out an NDA. This tech can produce really nice surface quality as compared to FDM printing and more importantly, you can print complex geometries without supports and end up with a uniform texture. A lot of outfits that you see advertised towards the DIYer are perfectly fine but they are mostly based out of China and you can say goodbye to your IP if you go thru 'em. SLS and/or MJF printing, especially with vapor polishing or vibratory polishing is where Id want to go for interior parts that you touch and feel every day. You can get there with FDM printing, but its a lot of manual sanding / painting to get a nice quality finish.

 

[MoCoNative]

The below post I made covers some of the details of retrofitting a charcoal canister.

Post in thread 'Charcoal canister'

Oct 10, 2014

The computer and vacuum switching valves controlled the canister. It is important as the others noted for capturing the expanding gas that comes off your gas tank on a hot day. It also provides the vent fro the gas tank to replace displaced volumes of gas if your gas cap still seals. The gas tank it self has three vent lines on top strategically placed so the tank will vent at any angle.

Do you still have the hardline crossing the top of the engine bay? I just recently re-installed all this stuff. I made a new hardline to cross the engine bay from fuel line. Do you still have the...

• MoCoNative

• 

My setup has worked great. The GM valve has been good. Do not vent straight to manifold vacuum. Us the EGR or vac advance ports on the carb for the vacuum trigger. That way it is not dumping vapors in when you start up and it does not dump vapors at idle, both scenarios will throw off your idle mixture. By using the ported vacuum on the carb it at least pulls on the vent line while you are romping on it and the engine does not care then. If it is a later 40 with the temp controlled BVSC in the thermostat housing you can route vacuum from ported vacuum to BVSC to purge valve. Then it will only purge after engine is up to temp and you romp on it. Which is exactly how the 60 and 80 series purge systems work. Proper venting at the tank is also needed. The vapor separators are also getting harder to find or have been lost on a lot of trucks. They are key to making the tank breath, and the three breather lines ensure the tank vents at all angles, so the separator needs to take that into account. Either three nipples to the tank, or tee them together.

A 12v solenoid is a cool idea, and can be had easily, but you are relying on the truck still having the emissions computer under the dash and that is still functions. You also have to have the second temp sensor in the head and the speed sensor on the back of the speedo in most iterations of the FJ40 smog system to trigger the original computers to do the purge. All of these parts can and will be missing on a lot of trucks at this time I suspect.

Eastern Beaver, Automotive Connectors - https://www.easternbeaver.com/connectors/ has plug shells for the three slot plug on the fender for the original purge valve, so a harness can be made, he also has the newer rounded two pin shells to plug into generic Aisin vacuum valves. I replaced one on my FJ60 that way.

Something like this: Pardon Our Interruption - https://www.summitracing.com/parts/smp-cp3051?seid=srese1&gad_source=1&gad_campaignid=1805983646&gclid=EAIaIQobChMIsZrvuuiTlAMVTACtBh1TqTiAEAQYAiABEgIsY_D_BwE is probably the simplest way to add a canister, line in, line out and the vacuum valve is right in the top. I don't know why all these canisters have gotten so expensive, these used to be much more reasonable to purchase. A similar canister was a good alternative for the 80 series, but they have gone up too.

 

[Pighead]

Bet I still have this one in a box somewhere

 

[procomsignathid]

my thought for the 12v solenoid for the purge valve was to marry it with the following:

• a configurable vacuum-switch that only closes when the vacuum is over a certain set-point (such as 10in), tied to a normally-closed relay. when vacuum is over 10in (idling etc) the relay opens and the solenoid valve loses power / closes
• a timer relay in-series that only closes after 10m of power-on

I think this would get close to optimal operating conditions (and would at least be an improvement of opening whenever the engine was on regardless of conditions) and would only need to be connected to the vacuum system and a 12v source. downsides is that its not getting any information about speed, coolant temp, and would still open during WOT, but low vacuum would pull less vapor anyways.

re: the vapor separators and the high expense of the charcoal canisters, that's one of my main drivers for this. I want a solution that isn't going to cost 100s of dollars, and Id like it to be serviceable.

 

[procomsignathid]

@Pighead I'll shoot you a DM, thank you!

 

[Pighead]

Bet I still have this one in a box somewhere

Found my spare. It's probably off a 55 if that makes a difference. I still run one but it just vents to atmosphere...

 

[procomsignathid]

@MoCoNative and any other carb experts... Can you elaborate on the vac advance port and the egr ports? The two ports Im using in my current setup is the little port on the base of the carb (that goes to the vacuum advance on the dizzy), I have that teed off to the control port on the vacuum-switched valve for the purge port. that opens a pathway between the intake manifold and the purge port. Is the base port on the carb commonly referred to as the vacuum advance port, or are my wires crossed?

as for the EGR port, I don't know my carb has one. It's an aisan carb, but clearly not the original (truck was desmogged prior to my ownership). I'm not sure all carbs will have an EGR port on em, but I could be blind, or maybe it was capped off and I just didn't know what I was looking at.

 

[timmyisinthewell]

Found my spare. It's probably off a 55 if that makes a difference. I still run one but it just vents to atmosphere...

View attachment 4131756

View attachment 4131758

It looks like that same p/n was used in both the FJ40 and the FJ55.

 

[Pighead]

Is the base port on the carb commonly referred to as the vacuum advance port, or are my wires crossed?

That's the "ported vacuum" source, at least, that's what I call it. Your ported vacuum is different from your manifold vacuum, you don't get any at idle, it comes on at weird times and it's not as strong as manifold vacuum.
I think that there was a time when only the Ca carbs had the EGR pipe, the Fed carbs did not. The pipe was in a spacer made out of the same phenolic stuff as the stuff the PCV pipe is in. The EGR spacer is on top of the cast-iron carb base and under the float bowl middle section My 10/'73 Ca carb had one but I cut it off and filled the hole with the JB weld...
Do you need the canister to vent to a strong vacuum? How 'bout just venting to a convenient spot on the air cleaner housing? Wouldn't need a check valve or 12 volts.

 

[procomsignathid]

Thanks for the terminology @Pighead, I think the ported vacuum is what I would advise most folks to use, but I need to pull some data on it. Ill connect mine up to a vacuum gauge and drive around to see when it generates vacuum. ideally, you purge the canister at gentle cruise, not WOT or idle, and when the engine is warm. As for dumping to the air cleaner, how strong is the vacuum in there? I set mine up to purge to the intake manifold currently (it uses a vacuum switch actuated by the ported vacuum). If the vacuum is not strong enough, eventually the activated charcoal will saturate.

 

[procomsignathid]

Been doing some modeling this week and some initial prototyping. Also, currently dissecting an early FJ60 canister to measure charcoal volume, check valve geometry, ball bearings / springs etc.

Here’s a few shots of the lid / thread prototyping. The outer edge of the lid will seal against the inner surface of the canister with an o-ring. Might do two o rings (thinking of the valley hybrid xfer case seal for parking brakes):

Im re-thinking a major design decision I made, and would love some feedback: All the 40-series (and from what I can tell, the 60-series too) canisters vent from the bottom. This makes the engineering dead simple, as there doesn't need to be internal plumbing within the canister (aside from check-valves). The GM canister we use as an aftermarket replacement has the vent up top.

I decided to put the vent up top on mine to reduce the likelihood of splash / water getting in there and fouling the activated charcoal, also to make it easier to visually inspect (dirt daubers) and potentially route the vent to a higher location if desired.

Im re-thinking that… Even in a deep water-crossing, a lower vent wouldnt let much if any water in due to atmospheric pressure inside the canister. Its like an old school diving bell. The vacuum from the intake manifold would slowly remove that pressure and allow water in for an extended deep crossing, but we’re talking water up to the top of the seats here.

Moving it down low would eliminate a SS316 pipe from the center (to route the vent port to the lower plenum), eliminate an o ring, simplify the charcoal filter/lattice geometry, and obviate the need for an internal vent support. I can find other ways to keep the splashes / dirt daubers out (likely a screen or baffle).

Thoughts? Do folks like the upper vent or lower vent more?

 

[MoCoNative]

The vent lines do come out the bottom. They then tie into a line either metal or hose that runs back into the front crossmember of the tub. On the 80 and 60 I think they drop down into the frame. The vent is important because it provides positive air displacement into the gas tank, so the canister is also filtered air for the tank. I always assumed the vent went out the bottom to allow natural drainage of possible water incursion or even condensation. Going into a frame member I assumed worked like the air cleaner inlet inside the fender on newer trucks, it provides an area where heavy dust is less likely to enter due to it falling out before entering the cavity. Also a low vent drains possible gasoline that could reach the canister or fumes towards the ground and away from the engine compartment.

 

[procomsignathid]

There's really just two connections to the canister that should have hoses on them (3 for late-model 40s), the connection to the tank (as you mentioned, connects to a hardline that ties back to the evaporative separator), the purge port which connects to the intake manifold or the ported vacuum, and the lower vent which should just vent to air in the engine bay.

this is a diagram from an FJ60 but it works the same way for the 40 series (albeit in earlier years, there is no carb bowl connection and less/no VCV/BVSV connections):

If your vent line is connected to the tank, the charcoal canister may not function correctly. Fuel vapor would make it into the charcoal bed, and the engine would pull vacuum on the purge port, but if the "to tank" port isnt connected to anything, the ability for the engine to draw in fresh air will be entirely dependent on check valves on that port. Even if it can pull in fresh air, that pathway would largely bypass the charcoal bed. In Toyota's designs, the port that allows vapors in from the tank is extended about halfway into the charcoal bed, so in theory it could still work... but I would just connect the tank to the tank port.

As for makeup air, the primary path for that should be the gas cap, which should allow air back in. The charcoal canister does serve as a backup for this path as well (thus the bi-directional check-valve on the tank port).

 

[MoCoNative]

You are correct, I was not implying the vent goes to the tank, but as you say at the end, the vent does allow makeup air to the gas tank.

As you can see check valve 2 in the 60 system allows air to travel back to the tank. Check 1 only allows vapor into the canister over a certain pressure. I do no recall the pressure of each check, but they do have a calibrated set point based on the spring, it is very low, but enough that the system is not just an open vent.

On the earlier FJ40 there is a pressure check valve in the line just after the separator. I have the 73 Emission book at home, I'll take a picture of the specs in it, but the cap air admittance is at a higher vacuum than the check valve. This leads me to believe the bulk of tank make up air was intended to come in the filtered charcoal canister. I don't think there are any check valves in the top of the early charcoal canisters. The manual does not indicate that.

The regulation of air movement from this system is also important and was assumed as a controlled vacuum leak to the manifold, too much free movement and it will lean the fuel mixture beyond what the carb was calibrated for.

 

[procomsignathid]

Thanks for the FSM pics, this is a nice way of pulling it together. I just dissected an FJ60 canister, both to measure the charcoal volume but also to get dimensions and spring rates on the check valve springs. 5mm ball bearings are stock, the springs themselves are only around 4mm in diameter, 10mm long, an compress about 2mm with the weight of the ball. Based on some back-of-the-napkin calculations and measuring preload in the inlet check (listed as #1 on the diagram up there), It looks like the cracking pressure is about .3-.4PSI. really low, and that's in-line with what I measured on the check-valve that they put in-line near the evap separator (it's more like .2-.3PSI, but I've got a digital manometer on order so I'll be able to get a lot more precise).

I believe the in-line check valve (OEM Fuel Vapor Check Valve for '75 to '77 Land Cruiser FJ40 FJ55 - https://www.cityracerllc.com/products/oem-fuel-vapor-check-valve-for-75-to-77-land-cruiser-fj40) is a belt-and-suspenders approach, but is primarily there to keep liquid fuel out of the line between the evaporative separator and the charcoal canister. I think, like you say, the check valves in the charcoal canister are doing the heavy-lifting here.

Net-net, my plan is to include check-valves, and I'm working on updated geometry for both to match OEM specs as closely as possible. Interestingly, there was also geometry for a check valve on the purge port, but I believe for cruisers with the extra emissions gear (VCV, BVSV, outer vent valve), it appears to have been omitted. I found an earlier post here where it was only included on non-CA-spec cruisers. I think it might be good to include, even without a spring, as a means of protecting the fuel vapors in the canister from a backfire (there should never be pressure in from the manifold to the canister), but I may be over-thinking this.

 

[charliemeyer007]

Springs - look up Hooke's law. I suspect that in 50 years the springs have relaxed some.

 

[procomsignathid]

Springs - look up Hooke's law. I suspect that in 50 years the springs have relaxed some.

Good point Charlie... I'm going to run the #s again. I have two springs, one that has held a ball bearing up its entire life, and the other that has sat atop one (albeit with some preload). I'll need to take an average of the two springs and go from there.

The check valve that admits vapors in from the tank should be stiff enough that when the engine vacuum is active and its purging vapors, the path of least resistance is to pull fresh air in through the charcoal bed to desorb the fuel vapors, but loose enough that the vapors easily get into the canister in the first place.

 

[Pighead]

On a 55 the canister bracket bolts to the inner front fender, towards the rear, near the big vent. The bottom drain connects to a hard line that follows the floorboard and ends, open to air, in the front body mount