1st gen tundra. P0453 water damage under drivers seat.

Need help with 1st gen fuel filler neck.

 

What about it? Are you fighting with the TSB where the fuel filler neck cracks, or did rodents chew your neck up?

 

Smoke testing has a leak at the plastic piece wrapped around the filler neck. No rodents present.

 

Should it be sealed? If so, what purpose would it serve to make a hose that is sealed at the end.

 

The fuel system is supposed to be sealed, with the cap as an emergency vent to valve either under- or over-pressurization, and a vent/purge solenoid usually closer to the engine bay in many vehicles.

Over in this thread, there's a link to a TSB that covers fuel filler neck problems, specifically with them cracking and thus leaking, leading to EVAP codes thrown. Here's a link to the info to save you some reading, but it's related to '03-'04 and I'm not sure if it impacts the '06:

• 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.

Not saying that's what it is. But on a modern smog-compliant EFI engine, I'd expect it to be sealed. If you want to know if that's your culprit, consider taping a plastic baggie over it if possible, or any other method to seal it. See if your code - since I'm assuming an EVAP code brought you here - goes away.

Generally speaking, though, rodents are known to chew all kinds of plastic bits on the tank to cause leaks.

 

Doesn't seem to match.

 

Is there a problem with your truck that caused you do a smoke test ?
What if any other issues are you having ?

 

P0456. I'm thinking now it's the vent valve on the canister being stuck open.

 

P0456 is often a faulty gas cap. And I don't recommend getting anything other than OEM. Others learned the hard way. And don't buy it on scAmazon or fleaBay.

You may want to inspect the canister for cracks too.

 

Did that. Smoked it and leaked from around it. Took everything apart and it was coming from the tube on the outside of the filler neck.

 

Around and behind it.

 

Is it something easy to take a pic of? I'm just curious to visualize what it is.

That code is for a small leak. Usually faulty gas cap, purge solenoid not sealing, loose or cracked hose, cracked filler neck... Smoke test is the way to go about diagnosing for sure.

 

Don't have a clue how to upload the photo.

 

Is it viewable?

 

I see the pic - which part is problematic? The split up the side? The lower tube? The upper tube?

 

Lower. It's attached to the outside of the filler neck but doesn't go inside. Since it's leaking under pressure I'm thinking the solenoid is stuck open.

 

Thanks....given P0456 is very much pertinent info, ask you consider adding P0456 to thread title. In the future those searching web or even this forum will be helped by that gesture when experiencing similar or same problem.

Top right area of thread....select Thread Tools

 

Just to get a better perspective, are you speaking of area about where red arrow is ?

 

No. Top left of that.

 

Thanks for updating thread title. It’ll help when folks search this forum for P0456 code.

It took a bit of memory joggle but then I recalled seeing you here before with EVAP issue….

P0453 code. | Toyota Tundra Forum (tundras.com)

I would think instead of "small leak" code, you would be seeing "gross leak" and code would be 455



Just to put this thought mentioned before in this thread and your other thread, have you replaced gas cap ?

Also could you somehow point to place on pic or better describe where your actually speaking of. Realize it could be a pain but a pic of yours would welcomed.

 

New cap.

 

New OEM cap at that, if I recall, so this wouldn't be the issue others have seen when they opted to buy Stanton or other brand caps.

I forgot we'd been down this before with you having the P0453 code. EVAP stuff can be whack-a-mole sometimes.

If this was a problem with the purge/vent, the ECU should detect it's stuck open or closed and throw a P0441, likely paired with another code for gross leak or excess pressure depending if the solenoid was open/closed.

That said, seems weird you had P0453 prior (high pressure in system), and now it's P0456 (small leak), at least if you did nothing in between. I can see how you'd want to blame the purge valve, but ... it should toss a code for that, and the current P0456 code seems valid if you're seeing a leak at the tank filler neck.

And about that leak at the filler neck, is smoke leaking out between the metal flange and the plastic? Or is it at a specific spot in the plastic body? Is it something you could tape over temporarily with electrical tape to seal it?

 

The medium sized tube on the filler neck is a fresh air intake for the canister vent valve. It is not designed to be sealed. The vent valve is what seals it at the canister side.

 

Correct me if I'm wrong, but the part Yota06 is showing in his pic is actually upside down from the actual orientation, which Bubba put a pic of. And by "medium tube", you're referring to the tube oriented on top in Bubba's pic, versus the lower tube in Bubba's pic, correct? I'm just looking at the push fitting on the smaller/lower tube in Bubba's pic, and it looks like the plastic quick-connects used for fuel and EVAP stuff. I'd expect that smaller tube to be the tank vent, i.e. the eye at the filler metal cup, so when you're pumping fuel in, there's a return vent to prevent backup/spillage/overpressure in the tank. Both the smaller tube and the central fill tube should be sealed by the gas cap when the cap is installed, part of the reason a good, quality gas cap is needed.

 

Oem on it. Vent valve is what I'm suspecting. Bout to tear it down and bench test it. I'll return with the findings.

 

Found it. Wiring harness pin on vent valve broke off inside the plug. That was why I had the p0453. It was grounding itself out. Now it's stuck open and allowing a leak and throwing p0456. Tracking down a new harness and vent valve.

 

Got a pic? For posterity. May give others a chance to see for future stuff.

 

Put it back for tonight. I'll get a close up and post it.

 

Left most line in attached picture is fuel tank vent

Middle pipe is the fuel inlet

Right pipe is vent valve fresh air inlet. Just carries fresh air to the vent valve. They run it up to around the filler area to prevent debris from getting in there but it is not part of the sealed EVAP system.

 

Ok...So...Funny story. Buckle up.
P0453 was the original issue. Basically a wiring issue. Not knowing this I thought it was bad gas cause it was shutting off. Put new gas in...no dice. Try clearing the code...no cigar. Put in a new fuel pump...nada. Took the evap canister out and unplugged it...No more code. WTF! Put it all back together and no code (harness was broken by then so no wiring issues) Did a smoke test and it was leaking through the air intake connected to the filler neck. (Vent valve).
Somehow during extraction I damaged the pin in the wiring harness. Went to a pull a part and got a new valve and harness and put it in. Code is back. P0453. Sumbich. Traced the wiring harness back to the cab and, Funny Story...(see attachment). The plug under the seat was full of water and frying itself. Port and polished and reconnected. No more code.