Fuel tank over pressurizing

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When you guys talk about swapping the hoses on the CC, are you talking the two hoses on the top of the can itself, or on the valve that sits directly above the CC?
 
The two smaller hoses that connect to the two nipples "tank" and "purge".

The "tank" port has a check valve in it to provide a small back pressure to the tank to help prevent evaporation. But it malfunctions and creates too much pressure in the tank.

The "purge" port does not have a check valve and air/fumes can flow through it freely.

On the plus side (or negative...depending on how you want to see it), swapping the cc hoses will make the engine run a tad more rich while driving, as the EVAP system feeding into the carb will no longer be functional.

Maybe less mpg.

Perhaps the "purge" hose should have a little air filter attached to it and left dangling so the carb can suck in that air during driving... because the carb jets were metered to run with EVAP working.
 
@LAMBCRUSHER
Can you provide an update on your charcoal canister refurb? Is it working well? Any issues?

I'm considering doing this since I have a spare (bad one) sitting around that I can refurb.

Also, any activated charcoal work or is there a certain particle size?

Thanks.
 
I also replaced mine with the gm unit and it solved the problem. I drilled out the third plug (that you can see in the picture above) so that i could keep all of the vacuum lines routed as toyota intended. Did this mod several years ago and it works great. Thr gm charcoal tank is cheap and saves all the hassel of messing with an ancient cannister.
 
Thought I should post here in this old thread. Ive owned my 83 FJ60 for a year now and same old problems as everyone. So yesterday pulled the CC out , blew air through the 2 nipples on the top and one on the bottom. The smaller top nipple I have running to a VSV and then onto the filter fitting on the inlet manifold. The other top larger nipple is the tank line and the lower nipple goes to a bell shaped fitting on the inner guard. I ran the tests like in the FSM and it failed on the check valve on the purge line to the inlet mani. I ran some shots of inox in there and blew it with compressed air both ways. blew the tank line out , checked all the hose connections in the rear quarter and took the fuel cap off and took it apart to find no safety valve in there or evidence that there ever was one. My truck always has the fuel smell but no leaking at the fuel cap but large vacume or preasure when i remove the cap, so much it bangs the gage float up and down in the tank when released. Also out of the blue the CC would just buzz sometimes for a minute or so when sitting in my shop. On testing i found applying vacume to the larger tank line nipple made this buzz.
Anyway I reassembled everything, ran the engine and let it sit for a bit unscrewed the fuel cap and felt a slight rush i think as normal. I then bypassed the VSV and ran the smaller purge line straight to the inlet manifold filter and the buzz started faintly and continued. I then put the hoses back to connect the VSV as normal. Drove the truck around yesterday and today and sofar no buzzing and no whoosh under the fuel cap .
Not sure yet but I may have fixxed the check valve or managed to clear a blockage . When i purged the CC with compressed air, it had a strong smell of fuel for quite a while.
This truck is Aussie market and i believe it has the emmission system similar to a FJ40-55 as in the FSM, I only have 2 VSV type solenoids.
Hope this has solved my problem and helps someone. Maybe inox fixes check valves? who knows.
Pic is of CC fitted to my truck.
Thanks to all the posts on here folk could not have even attempted to work this out otherwise.

IMG20210312103547.webp
 
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