My new driver son went nuts trying to get every ounce of gas into the tank. So much so it looked like the gas station scene on the Zoolander film. lol The codes started shortly after.

After replacing most if not all of my tubing I took out the canister and looked for cracks. I found one small one in the corner so cleaned it up and used that "as seen on TV" rubber stuff. Used it on other projects and it is magic.

I was popping a 446 after every 120-150 miles or so. Now at 300 and no codes so still with fingers crossed.

I also wanted to add my mpg went up from 16 to the latest 20.5. This was my wifes (5 speed)car previously and she got 19 all the time except for hyway driving which came up 17 at 80mph.

So I'm thinking fixing this code pays for itself.

Sorry to hijack a old thread but being a new user I can't start my own yet.
I've been using this site and others for awhile for research and its been great. I've got a '01 Tacoma, a '12 Sequoia and I recently purchased a '01 4Runner with 144K miles for my son.
His 4Runner has been throwing P0440 and P0446 codes. I swapped my Tacoma's gas cap with his and my truck didn't throw the CEL and his didn't stop so I think I can rule that out. The filler neck appears to be in great shape.
Today we put 6v to the CCV and VSV under the hood, as well as to the VSV mounted to the charcoal canister. Each clicked when applied with voltage. I also checked that each of the plugs feeding the switches had 5v +/- when the truck was running. We pulled the charcoal canister and inspected it for cracks as well as inspected all the hoses - everything looked good.
With the cannister on the bench I tested it for leaks. Using soapy water and a bit of positive air pressure with my mouth, I noticed air leaking around the two ports where the mechanical valves mount. See attached pic with red circles. I pulled each of the valves out and cleaned the ports and the o-rings - they were filthy.
My question - shouldn't the canister be completely airtight at least to the pressure I can create by blowing? Could the leaking air from both of these ports cause the P0440 and P0446 codes?
We have not smelled any fuel vapors, the canister granules appeared to be dry, the cannister itself didn't stink of fuel, my son doesn't overfill the fuel tank at the gas station, and the truck itself runs great.
I ended up cleaning the o-rings and adding a bit of flex seal at the connection above the o-ring in an effort to seal up the leak. I figured it couldn't hurt.
Thanks for any feedback

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I have a 2000 4runner that has a different style of canister but I checked mine for leaks similar to how u did with yours. In my case I had a pin hole leak and once fixed my PO446 went away. IMO if yours leaked when pressure testing that is what is causing the PO446 code. I think once you fix the leaks that code will go away. For the PO440 I have fixed that code a couple of times on my sequoia by replacing the gas cap. It sounds like u got that part fixed. Good luck

MikeM

Thanks Mike.
I wasn't sure if the cannister was supposed to be totally sealed or not. Sounds like it is supposed to be.
Fingers crossed. Maybe Flex Seal founder Phil Swift can add charcoal cannister repair to his commercial!

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Wish me luck. Check engine light, VSC, ABS lights came on all together. Second time ever I've had this come on. First time was in 2013 and the dealer said the secondary CAT was failing and needed to be replaced. After a few searches the O2 sensor right before the muffler was suggested to be changed.
Last time I changed this sensor was in 2013. After replacing the sensor and clearing the codes it never showed back up until a week ago. So that's almost 10 years and easily 100k miles.
Below is a picture of the old sensor I just removed and replaced. I’ll post back soon to see the long term on this.

Depending on your environment the gasket surfaces of the gas tank rust.

That will also cause the EVAP leak codes.


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Thanks. I'm hoping I can avoid dropping the fuel tank but who knows. The remainder of the 4Runner is spotless - no rust, been treated very well. Based on how clean things are underneath, I'd be shocked if the top of the tank is in bad shape.

My 97 SR5 build and repair thread shows the process. My tank looked pretty good for the rust belt but rust was measlesing under the rubber gasket. I had to drop it to weld a new lower control arm mount on. I had seen a few threads where that was the source of the vacuum leak and decided to preemptively redo both rubber gaskets.


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Just a quick follow up - still no CEL. Hopefully the leaking o-rings on the charcoal canister was the issue.

Where did u get replacement fill and is there a spec on amount

I got a high quality dense charcoal for aquariums on Amazon. No spec on fill. You cannot overfill it is just pushing the vapors through the media.