Looking for Somone Who's Changed a Charcoal Canister

Please post any links you find on PriusChat about doing that... As best I can remember, we've always just said replace the whole tank/system as a single unit for all problems because its easier to do that swap from a low mileage wrecked car than taking apart that system.

 

What motivated you to undertake this unforgettable adventure?

 

Wait a minute If I'm not mistaken this is similar to my Siena van I have two sitting here that I can take out but I haven't done it just because and I do believe they will come separately from the tank It's a rectangular sheet metal like box affair that has the vacuum switching valve the charcoal canister related hosing and I'm sure some other stuff. I don't think you have to take the whole tank out You may have to loosen it so that you can slide the thing up kind of behind it if you will The rear portion of the canister assembly and it cheap metal rectangular assembly go up above the trailing edge of the tank if I'm not mistaken so removing it shouldn't be a thing but I guess if somebody wasn't studying very long they could just think that would be the quickest thing to do because I'm doing bolts is pretty quick of course if the tank is full and things like that just becomes a little more problematic You don't want the tank coming down when you blast out the bolts so that's just to loosen them or the straps if you have to to make a slight space just slide the canister assembly out Don't forget to unplug and debarb all your hoses.

 

Yes... But Gen2 Prius in the US have a rubber bladder to minimize, nearly eliminate, air displacement when filling the tank. I suspect that's why not many have found much interest in doing this job.

 

When the tank is empty, it has air in it. While filling up with gas, the air has to go somewhere. The canister releases pressure in the tank. When you fill up, the air in the tank goes into the canister. When driving it releases it.

There's probably some really good repair manual explanations of how that whole system works. I don't know that I'd go yanking that fuel tank just yet, but if you do, I hope it works out well. Not a difficult job, just a pain in the...getting it back in sometimes. (I've done a Gen 2 fuel tank 2x, with the cars lifted on jack stands).

 

As the bladder expands within the rigid outer tank, the air surrounding the bladder needs a place to go, and there is still a whole onboard refueling vapor recovery system involved there.



I agree that blindly waving off serious hard-to-fill problems as "oh, that's the bladder" is usually the wrong call. The bladder can be the answer for mild questions like "how come I could fill 8.3 gallons last week but only 7.8 today?". When there's a serious issue preventing refueling even a few gallons, or sloshing them back out at you, generally something in the ORVR system needs to be fixed, and when it's fixed you won't have that problem anymore, and can go back to just the usual bladder questions about slight differences in how full is full.

But beware, the canister itself will not always be the root of the problem. We've had threads here where the refuel check or fuel cutoff valves were the culprits.

 

And what was said above about the evap system was the case then my car's EVAP system would be dead in the water and completely failed and full of fuel because I feel my generation twos up when I first get them like I'm trying to stretch the tank till it explodes all the way up until I can see it in the filler neck right before it dumps out on my foot or the side panel and the tire I can stop it right at the top no air bubbling or nothing completely full no air anywhere that I can tell and everything seems to be working fine I have no evap codes no solenoid problems nothing car runs great not a light on the dash I know that evap canister is very similar on my sienna van and you can get it down without removing a bunch of stuff in the pictures it almost looks the same if you care to look at a sienna van evap canister picture It is well quite similar I don't even think you'd need to loosen the tank to get it off of the Prius and I think the hose is going to it should be relatively easy to do I've got one out here to do to remove for the part so I'll know in the next few weeks or so when it warms up a little I'll go out and take it off

 

Stop!

How, when filling the inner rubber-plastic bladder, were you able to pour gasoline between the plastic bladder and the fuel tank body?
Is the inner plastic bag damaged?

Then, logically, when filling, the internal air will just start to come out into the plastic bladder, and then out through the filler neck.
I believe that ChapmanF is right in that the problem is not in the canister itself, but in the valves that do not allow the air located between the bladder and the fuel tank body to quickly leave the space, thereby freeing up space for fuel.
And in winter I also noticed that the plastic bladder is more rigid and less fuel actually enters the fuel tank. But if you wait a little, then the fuel is added to the tank in small portions.

 

My understanding was the space between the bladder and tank is not supposed to have gas fumes in it. There's even a sniffer that confirms this and will throw an error code if any is detected. It would NOT make sense to have a charcoal canister for that specific system, only for air displacement on the inside of the bladder.

But in looking at your graphic it appears as though the carbon filtered air that's displaced is being used in that space between tank and bladder, which seems odd and I'd like to learn more. But all this is a tangent.

The real question is why would OP need to replace the charcoal canister on a system that so much more advanced than the way this system works in most cars? Or even more to the point, have you ever heard of someone needing to change the carbon filter on a Gen2 Prius?

 

I have not. But I've heard people use the logic of slow fuel in tube enroute to tank to slow must be EVAP issue soaked canister etc .I've seen soaked. Cannisters dry right out on vehicle in about 1 hours of driving and vacuum pulling on system .

 

Where is that sniffer, and what error code is thrown by it?

I know there's a pressure sensor, which is used during the routine EVAP system testing that checks for leaks (by watching the pressure response under different vacuum and solenoid-valve conditions). I'm not aware of any sniffer to recognize gas fumes.

As you've noticed, it takes a little widening of your assumptions to fit what Toyota actually built.

The illustrations I use are from an 18-page University of Toyota course module you can find in the Technical Library section of TIS. https://priuschat.com/wiki/toyota-service-information-and-where-to-find-it/

It's not always certain that the canister is what needs replacement when there's an ORVR refueling problem. Pump nozzles have a sensitive pressure-responding mechanism that shuts them off, and there are a bunch of Prius ORVR components that interact with that on purpose so the nozzle shuts off when it should. When that isn't going right, some diagnostic steps are needed before assuming the culprit is the canister or the refuel check valve or the fuel cutoff valve or whatever.

Although Toyota clearly warns about overfilling and the risk of needing ORVR system repairs, there are always people like Tom reporting "well, I do that all the time and nothing goes wrong." Of course, we also have people like ToyotaGal who started one thread about how she couldn't fill more than a couple gallons into the tank, got it fixed by replacing the valves as needed, confirmed it was working fine once repaired, ignored advice from several members to lay off with the overfilling, and started a new thread for the same problem eight months later. :/

 

I don't know man when I get mine I can't get before or 5 gallons in them and I just keep pegging them full in the summer time in North Carolina and let him sit in the sun and stretch everything back there that can be stretched out I guess seems to make sense to me and now I can pull into the station at 300 and something miles 350 something like that and peg 8.3 gallons in the car almost immediately then it burps I give it a few more squeezes till it's resting at the filler neck hang the hose and cap and go. Anytime the check engine light is on in my sienna van it generally has to do with that evap solenoid back next to the charcoal canister in the same rectangular container as the Prius has I do believe I don't have the van here to compare the two but they look pretty close mounted similarly if I'm not mistaken.

 

For a pretty penny I had a local guy do this for me. It did not involve any of the ornery particulars being thus far discussed, so maybe your situation is different from mine. https://priuschat.com/threads/p0446-and-techstream-tbp-fail.194517/#post-2758112