P0440 Evap Code Solution

Hey guys, I'm posting this for future people searching for a possible solution to only having a p0440 code. I hope this helps, if you mess your truck up doing DIY stuff, you assumed that risk on your own. Thanks!

Background: Recently my truck popped the evap code p0440 indicating that there was a malfunction in the system. My gas cap is less than 2 years old and is a replacement OEM Toyota gas cap. My truck has close to 200k on it and is a 2002 Prerunner DC v6 though the evap systems are the same.
I had visually inspected all of the lines going to the evap system and manually checked the vacuum switch (I forget what Toyota calls it.) I also figured there wasn't something wrong due to there being an absence of incorrect purge flow, or other related codes with sensors etc.

I searched online for a week straight including this website and found most answers calling for throwing a new charcoal canister on the truck. This would have been a waste of some $400 or more.

Symptoms: P0440 code and a smell of gas coming from some where near the rear tank that could be smelled between the cab and bed as well as in the driver side rear wheel well. Also possible slight idle change but no hard evidence of that.

Solution: The roll over valve aka check valve. For my truck, a 2002 DC Prerunner V6 the part numbers listed on all online part diagrams were incorrect. My truck required part numbers: 77390-35010 Check Valve, and 77177-33010 Check Valve Gasket. Both of these parts are listed for 2002 4runners only... I have no idea why this is but I do have the double cab. The problem is that they fail by losing the ability to maintain vacuum as well as crack at the top causing fuel vapor and possibly fuel to leak out causing the fuel smell. So they fail internally and externally. Pic of the valve at the bottom of the post.



How I changed it out: I elected to remove the bolts to the bed on the drivers side and loosen the bolts on the passenger side allowing me to lift my bed and place a 4x4 block between the bed and frame mount to the rear of the wheel well. This allowed me to lay over the wheel and pry the valve up out of the tank without dropping the tank. Also, you will need some dialectic grease or other rubber safe silicone because the new gasket and valve have a pretty tight tolerance. I placed the gasket onto the tank and then slide the valve into the gasket.

 

Glad I convinced you lol

 

I'm working on one now.
It's a crew cab , 4x4.
Lifting the bed is so much easier than dropping the tank
On this one it looks like the roll over valve is good. Lots of dust on it and no sign of a leak.
What I did find is the the rubber flex hose, going from the filler pipe to the tank, showed gas stains.
Everything was dirty, so I washed everything down.
Waiting for it to dry off.

 

Are you asking about this one ?

 

This may help
https://us.autologic.com/news/toyota-tacoma-evaporative-emission-faults

 

Hope you can find your VIN#
http://japan-parts.eu/

 

I have that code in my 2001 v6, It does not have this part. didnt start till 2002.

Any ideas on what else it can be?