EVAP code help

Chiming in/ asking a question as I've been fighting the EVAP fight for too long now... I don't mean to hijack your thread but it could potentially come into place for you as well.
I've installed a new Toyota charcoal canister, VSC under the hood, gas cap, filler neck, gas tank and roll-over valve. I continue to have faint smells of gas fumes from behind the cab. I've performed a smoke test with inconclusive results.

To the question - When inspecting, I occasionally see dried fuel markings around the fuel pump. I've replaced the gasket two (maybe three times now) but I've never felt really confident when tightening down the screws. When I use a small ratchet by hand, it seems that even when the screws are just starting to snug up - the gasket is already squeezing/ deforming from under the lip of the fuel pump cover. If I only screw them into the point where the gasket maintains it's shape, it seems like the screws wouldn't be tight enough.
TLDR: Any thoughts or procedure to follow to get the (8) fuel pump screws tight enough without deforming the gasket which could be leading to EVAP codes?

 

I ran into an issue with that gasket as well. I didn’t get an issue with warping though. I just used sealant and really got a good seal going on and then painted the whole thing. I haven’t seen any fuel or smelled any either since then.

 

acs118, have you replaced any of the rubber hoses from the canister to the gas tank or from the 2 EVAP lines along with the fuel line? The EVAP and fuel should be metal from the engine compartment to just behind the cab. Most of the hose on my '04 where dry and cracked especially at the fittings. I replaced the hoses and used stainless aircraft clamps instead of the OEM clamps to fix my EVAP issues.

 

Not wanting to start a new thread that will only make things harder to search for so I'll put this here. I have a 2003 base 5 lug with a 2.4. auto trans. No performance problems, but I was getting PO 441, 442 and 446 codes. Gas cap ring and area was cleaned. Vehicle only has 75,000 original miles. After cleaning the cap I reset the code, but now I'm still showing pending 441; 442 and 446 codes as well as the dreaded 420 code.

I'm wondering if someone can tell me what these evap parts in the pictures below are on a 2.4 engine?

What's the green plug #1 and the small rectangle black box #2 on the inlet line to what I think (in next photo) is the VSV (blue #1 circle)? And what's the other switch (#2 in blue) that sits just above the #1?

 

Red 1 is test port
Red 2 Check Valve

Blue 1 is Solenoid VSV Valve
Blue 2 is Solenoid Valve

You can also try having a smoke test performed on the truck. My dealer wasted my time and told me everything needs to be replaced.

You can do this in steps to see if the code repeats until you find the root cause

My fix was to start by replacing the two valves located in the engine compartment.

Replaced all EVAP hoses and clamps

Replaced solenoid valve on the canister

Replaced gas filler tube and rubber elbow at tank

Finally replaced gas tank, the top of the tank was pitted. ( if you go this route, replace the tank straps and fuel pump as well).

No more codes

 

Thanks for that info. There is a reasonable shop by me, so I guess I'll start with a smoke test.

I did notice when I pulled the line from the tank to the blue #1 above (VSV) (and had the truck warmed to operating temp) when I put my finger on the VSV inlet I did not feel any vacuum. Suggesting to me that VSV is not opening as it should. Does the blue #2 solenoid have any vacuum? Or is that just an electric switch based n temp or something else?

 

The valves open and close allowing for the fumes inside the gas tank and charcoal canister to be burned off when the engine is running. There is not vacuum per say. When the engine is first turned on the EVAP system performs a test, by applying pressure to the EVAP system and it has to hold that pressure for a certain amount of time. If it doesn't then, you will get one of the codes you are seeing.

Since the truck is 20 years old, I will guess that you have a bad VSV valve in the engine compartment, a bad VSV valve on the canister (lexus replacement part available). All of the clamps are rusted and the ends of the hoses are most likely cracked,

I used stainless hose clamps and fuel line hose to replace all of the EVAP lines. There are two EVAP lines that run underneath the cab (drivers side), inspect the lines and makes sure they are clean, no rust spots. One line goes to the tank and the other to the canister.

Look at the fuel filler, is clean or rusted?

 

Many thanks for your informative reply. I must say your comments are very understandable and very much on point. I really appreciate that. I will look on McMaster-Carr for hose clamps/clips when I figure the right size. Same with figuring out the ID/OD of the EVAP hoses. I'll order some correct EVAP lines. I'll get a quality VSV valve. From there I'll continue to work on the 420 code problems. I really need to check the exhaust carefully before suspecting the cats.

I will have a smoke test performed and hopefully it's not the charcoal cannister or the top of the fuel tank. But if it is, I'll fix it. I will check the fuel filter.

This 5-lug was owned by a 90-year old man and it sat for many years. It was in too good of shape for me to pass on.

While I'm mainly a 4X4 Tacoma owner, It was in nice shape, so I had to buy it. Sorry for the double pictures!

 

I have the p0440 code in my '01 2.7. Im pretty sure there's a small leak in the catalytic converter that I had patched with JB weld, although I don't think I mixed the stuff well enough and that patch fell off. I have other patches on my muffler that have held up. Does anyone know if a leaking cat can be the cause of the p0440 code? The more i read on here the more my head begins to spin due to the amount of things that can throw these EVAP codes. Thanks in advance

 

Pretty helpful thread. Going to dig into my p0446 by starting with a new OEM gas cap and clean up some crustiness on the filler neck, but I am sure I won't get off that easy. Hoping to post my solution in here soon.