EVAP/Tank Vent Nightmare

[djaye.]

So I've been going through my Dad's highly neglected 2001 4runner Limited over these past few weeks. Gusseted and painted the nasty frame, rear axle seals, ebrake cables, springs and Bilstein 5100 all around, replaced every single brake line on the vehicle, as well as a full service and some other stuff I'm forgetting.

But there is ONE thing I still cant get right- the tank fill issue (which was actually the final straw that got him to surrender the truck to me for much-overdue repair). About a week or two before I started work on the truck, the tank started to act up during fill-up (seems to be common with these trucks). You can only fill it S L O W L Y, with the gas nozzle pulled out about halfway. Not 100% but I'm also pretty sure it had some type of EVAP code causing a CEL at the time I started work.

Once I started work on the frame and had the tank dropped, I found literally the worst filler neck I've ever seen. The large vent line was missing a 10" section, just completely disintegrated to nothing. And the remaining three tubes would just crumble in your hand with a light squeeze. Also found the two larger EVAP lines (the long ones that go up to the engine bay) were in similar condition around the canister. Cut about 12" of bad material off of them and repaired with EVAP hose. Also replaced any other suspicious looking EVAP hose back there along with the complete filler neck assembly, of course.

Still won't take gas. In fact it might be even worse. Tons and tons of searching online, I'm willing to try anything. End up replacing both valves on top of the tank- the "fuel cut off valve" and the other breather/check valve thing (the big one with two hoses coming off it), as well as their respective grommets/gaskets. Also inspected inside of flex hose because I did see one instance where the brown coating inside de-laminated and caused a blockage. STILL NO GOOD!

Finally, I looked into the canister. The Toyota testing procedure looked super annoying, and I found a good deal on a complete low-mile unit complete with VSV and bracket. So I fired the parts cannon one last time, convinced this would do it. NOPE. I'm losing my mind over this bs.

Does anyone have a diagram for the EVAP hoses back by the tank and canister (I could only find engine bay EVAP diagrams) so I could quadruple check my routing because that's literally the last thing I can think of.

Sorry for the long post but wanted to give all the details of this disaster, any help would be GREATLY appreciated!!!

 

[jsukey]

I had that same issue with my '02 at 140k. I was told that topping off the tank after it was full was the culprit. Something that I had always done out of habit. It pushes fuel into the canister itself. Anything other than vapors are bad for it. Are you sure that the canister that you swapped in was in good condition? I've never done it on my '00, and it fuels up just fine, even after 274k miles.

 

[Buckaroo]

So the obvious thing to go after is clogged fuel tank vent. On different models, have heard of spider webs in vent tube restricting air flow....not sure how that relates to our T4R's. Did have a situation on a Corolla where maybe a cap from a fuel additive container had been dropped in tank and was stuck in the entry to the fuel tank from the fill tube. Disconnected the fill tube, pushed the obstruction into the tank and issue solved.

Buckaroo

 

[djaye.]

I had that same issue with my '02 at 140k. I was told that topping off the tank after it was full was the culprit. Something that I had always done out of habit. It pushes fuel into the canister itself. Anything other than vapors are bad for it. Are you sure that the canister that you swapped in was in good condition? I've never done it on my '00, and it fuels up just fine, even after 274k miles.

That's interesting. I don't *think* it gets overfilled too often but you never know with these gas guys around here. The canister I replaced the original with was ridiculously clean, low miles (with a warranty), and didn't feel especially heavy or reek of gas. I'm fairly confident it's a good part (literally anything is better than the filthy, rusty, dryrotted POS I pulled off of there).

 

[djaye.]

So the obvious thing to go after is clogged fuel tank vent. On different models, have heard of spider webs in vent tube restricting air flow....not sure how that relates to our T4R's. Did have a situation on a Corolla where maybe a cap from a fuel additive container had been dropped in tank and was stuck in the entry to the fuel tank from the fill tube. Disconnected the fill tube, pushed the obstruction into the tank and issue solved.

Buckaroo

You know, I remember a while back Mazda sent me a recall pertaining to EVAP issues from some dumb ass spiders setting up shop in vent lines on my 6. I probably should blow everything out one more time to be sure.

I replaced both of those valves on top of the tank as, from what I understand, is how the tank is permitted to "breathe". The ONLY line I didn't really mess with is the small one that goes straight into the tank via a metal elbow (no valve)... Anyone know what that specific line does???

 

[Chief Yota]

I've been going through some EVAP troubleshooting as well.. Here's all the pages out of a 2002 FSM regarding the EVAP system, hope it helps.

<a href="https://imgur.com/tmJnBjE"><img src="https://i.imgur.com/tmJnBjE.png" title="source: imgur.com" /></a>

 

[djaye.]

I've been going through some EVAP troubleshooting as well.. Here's all the pages out of a 2002 FSM regarding the EVAP system, hope it helps.

AWESOME! I'm gonna sit down this weekend and go over everything in here with a fine-toothed comb. Will report back, thanks so much!

 

[djaye.]

Ugh, still no luck

The ONLY thing I see here that's a little suspicious is the "Air Drain Hose" (the large hose coming off of the can.

Mine has a Y fitting in it with a large hose going up to the filler neck and a small vacuum hose branching off and going back to one of the valves on the can. In these diagrams, it appears as if the big hose is just open to atmosphere. I have seen other Toyotas (passenger cars) with that exact EVAP hose just being open (with a little turn-down spout pointing towards the ground), but then what would I do with the other (filler neck) end and little hose at the Y?

This replacement can I got also had the Y fitting and small hose so I really doubt this is the issue (parts deff look OEM), but just for lols I'm gonna disconnect them and see how it fills...

 

[RCopp17]

OP, Any updates with this? Chasing a similar issue with my ‘01. Thought it was the fuel neck as I was told a while back I was on borrowed time. Brought it in and it wasn’t the neck. Now I’m getting quoted $700 for a new fuel tank (plus labor) and being told that’s the culprit. Thanks for the help!


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