Charcoal Canister Overflow

I have a 1990 toyota 4x4, 4 cylinder, 22r engine.

What would cause my charcoal canister to overflow? I also get bad gas mileage to boot. I know the canister traps fuel vapors but what could cause it to trap so much it overflows? Can I just get rid of it?

Thanks very very much in advance.

Are you overfilling it?? Don't try to get every drop you can get in it!! Stop at the click!!

Are you overfilling it?? Don't try to get every drop you can get in it!! Stop at the click!!

Oh no, not overfilling at all, as a matter of fact my tank is nearly empty and its overflowing.

Check all the vent lines and make sure all are open and canister is not clogged!!

Regarding your overflow problem, if you have for any reason been putzin around that thing and gotten the lines mixed up when you reinstalled them, you'll get a gusher. When I did that, I think i remember getting the tank return line mixed up with the vapor line and ...
Anyway, I drained the thing, put everything back to right. That was many thousands of miles ago, so no harm done that i could ever tell.

I looked at it this morning closely and I think the lines look right, I matched them up when I took out the old one. I started to read some chilton manual stuff about it. It said that after the engine tempurature reaches 129 degrees, a valve opens up to let the vapors trapped in the canister to flow to the intake manifold.

So since I didn't overfill mytank, and since the lines look correct, it must be this valve, I'll also replace the pcv valve. I guess if the valve didn't open at all when the engine was warm it wouldn't cycle out the vapors trapped therefore the vapors would just stay and not go anywhere, I'm going to experiment, mua ha ha ha.

Thanks for the help so far, much appreciated.

Ahaaa! You were putzin around! You need to define overflow for us. It sounds like liquid (gas) is coming out of the canister somehow. If so, where from? If not, then what is it that is overflowing? Whether the valve you're talking about is faulty or not, I don't think you should be getting any liquid out of the thing anywhere. "Vapor" yes, liquid no.
And yeah, I thought I had them matched up right also...

There is a rubber hose that is coming out of the very bottom of the canister that goes all the way down to the ground. Gasoline pours out of this hose. It doesn't happen right away, I need to be driving some for it to start flowing. I already replaced the canister with a new one, and it still pours out gas with the new one. The canster was fricken 300 bucks!

OK, it's obvious now that there's a little more goin on with your situation. It sounds now like this was a pre- existing problem of some kind. More info or history will help.
For starters, is the rig new to you and it was leaking when you got it or something, prompting the purchase of a new canister? ($300-yikes!) If not, what else was goin on that made you do that? Did you initially do some other work that involved the thing? Has the mileage always been bad or is that recent? If you truly got the hoses back the way you found them, they may have been wrong to start with from whenever. It's those kind of details that will help. I still think you've got a line mixed up somehow. It happened to me and I'm not exactly stupid about this stuff, altho I was that day.
Gas pouring out the canister will wreck your mileage for sure. In any event, raw gas in your engine compartment is never good.

Ok, lemme give you a little background. The truck aint exactly pretty, its a beater for the winters out here in the midwest. When I bought the truck, almost for as much as the canister, it never had a problem with the canister in over 10,000 miles since I first started driving the truck. It's never had bad gas mileage until now.

I've worked on it alot, but mostly with the brakes and interior. Then one day I smelt gas, looked under the truck and noticed a puddle, I investigated even more that day and noticed it was coming out of that rubber hose from the bottom of the canister. I read in chiltons that the canister should be replaced after so many miles that it can become clogged or what not. So I replaced it. When it happened again, thats when I became suspicioius.

The truck is old so I figure one of the vales is probably fugged up. If I had a blown head gasket is subtle or obvious?

Thanks for your help.

You're keepin me up at night now. I really don't know what this is. But I still think you've got to rule out once and for all any possibility of mixed up hoses. I say this because, again, I had a perfectly working system, did some work, head gasket or something, mixed em up and had gas pouring out of it. I drained it, blew low pressure air thru it for awhile, and it's been fine ever since, 210,00 miles. Whether my valves are good or bad, who knows? Who cares? Remember, we're supposed to only be talking "VAPOR" here. This is mostly an air quality emissions issue. Find another rig like yours, compare, get a better book,with good emissions system pictures ( Haynes manuals are a good cheap choice that I feel are better than the Chiltons), whatever, just rule that out. And. just for grins, loosen or remove your gas cap for a short drive, and see if that makes any difference. It's just a feeling, but if you're building really high vacumn in your tank, it could be doing something weird there. If this helps, try replacing your gas cap. Some of my best fixes, I've never understood all that well...

Head gasket problems? if it isn't obvious yet, it soon will be. In my experience, you'll start getting a coolant leak down the driver side of the block, as the gasket is pretty narrow right there in the middle. Pretty quick, you'll get a heavy, lingering, sweet smelling white exhaust "smoke", especially when you start up. The pressure in the system is seeping coolant into a cylinder after you shut down, and it burns off when you start up again. Number 2 cylinder is where I always have problems. This is not absolute, just my experience. Overheating, coolant loss, etc, in other words, not real subtle. Heading off to the north edge of Alaska for a couple months for work, so this is last post for awhile. Good luck.