2004 SR5 V6 AC evap leak

2004 EVAP leak. I've had a small evap leak code all summer, getting close to inspection time, so it's got to be repaired. FWIW, I replaced the fuel filler cap months ago. I made up a DIY smoker and teed it in next to the factory test port. Engine off, the only smoke I can see is in the area of the filler cap. Looking from beneath, it appears to be coming out of the plastic surrounding the fuel filler neck. I cannot see the origin directly. It's a challenge to inspect the area around the vent canister, and my smoke production was fairly anemic.

Inspecting the filler neck from outside, everything looks pretty good. I sanded the cap mating surfaces and applied heavy grease when this all started - it's all smooth to the touch (even though it looks corroded). Looking down inside, I do see what may be some corrosion where the small line tees in to the fill tube.

I'm failing miserably at getting an image to upload, here are links for Imgur and Postimages:
https://imgur.com/hkzbCHd
https://ibb.co/XSPF78L

Thanks!

 

Didja see the TSB in the info vomit thread?

• Cracked fuel filler neck TSB for 2003-2004 trucks. See here. Causes P0441, P0442, P0446 codes. But also check the 'RODENTS' section two bullet points down for another possible cause.
• ....
• RODENTS: Lots of plastics, wire sheaths, etc. in these trucks use soy-based plastics. If you have rodents nearby, or you park outdoors regularly, it's not uncommon for them to crawl in the opening under the intake manifold, where the starter & knock sensors live, and chew up the wiring (no start, knock sensor circuit codes). Likewise, they love nesting on top of the gas tank, and they'll chew up both the wiring like this, killing the pump (no start), and chewing up the tank tubes/plastics like this (EVAP codes, EVAP small leak, EVAP large leak). They'll chew through the gas filler neck, which will also throw EVAP codes, like this. It's common enough we can share exact photos of it, and there are more where those came from.

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It's more than likely the TSB than it is chewing, but both should be checked.

 

Yes, I think I've read all the pinned posts at one time or another. As to my ability to retain the useful bits... the jury's still out on that one

I appear to fall in that range
https://ibb.co/bsbtFxQ

The prior owner's record indicated a gas cap replacement at some point.

It appears that freeing up the neck and giving it a close visual inspection is in my future.

Thanks

 

Quite possible that may be in your future. However, just a point. If that image you linked is accurate, and your VIN ends in ----------S435724, unless I'm reading the TSB wrong, your truck isn't impacted. For your VIN prefix (5TBBN4-----) looks like they fixed the problem starting with VINs ending --------S434414. 435724 is higher than 434414.

But I admit two things: (1) It's Monday morning, I'm slow on the uptake and a little scatterbrained, and (2) That's not to say your truck isn't impacted, you never know what a previous owner or their mechanic(s) may've done.

 

"435724 is higher than 434414."
I concur - you had all cylinders firing on Monday

 

Since I need an inspection sticker, I ponied up a Benjamin and got a proper smoke machine. Right away, it identified an underhood leak - a split vacuum hose right at the manifold vacuum hard line (a foot above the EVAP test port). Changed out that section of line (hard as a rock, kept splitting as I cut it back w/ a plastic tubing cutter). Still have just a little seepage coming from the filer cap (which I also had replaced again - with one from the dealership) and also from the neck, right at the top. Reset the code and kept an eye on the readiness monitor with the Xtool D8, and she completed. woohoo!

 

Good job! I recently replaced all of my vacuum lines under the hood just because. My truck is older than yours, so it was time. They were hard as a rock and brittle.

 

Smoke machine was 100% the right way to go about tracking this one down, and a good reminder to everyone, our trucks are old enough now to warrant scrutiny of the vacuum hoses. I actually need to look at mine, between the booster and manifold.