Very thorough diagnosis. I am/was chasing the same hissing sound on fill ups. I just put a cheap inline fuel filter on the tank vent hose that goes to the charcoal canister. Until I understand more about the system, I don't think I will mess too much with it. At least we know our fuel tanks won't split.


Also the cinematic explosion scared the $#*^ out of me. Cheers!!

You blowing it in the wrong port. Blow air into the "tank" port, cover the purge with fingers to clean

The bottom hose is the front axle ventilation.

I have a 91 & i put the GM charcoal canister and mine runs better no more fuel smell or pressure build up

The explosion got me, haha. Im in the middle of trying to figure mine out. Ih8mud said if pressure conditions not gixed it could crack tank.

I have the same with 2 different LC. On the first, I had replaced the Toyota canister with a GM part that fit ok. I don’t recall it making a significant difference to anything, other than no hissing sound when unscrewing the gas cap. I left it alone on the current LC. Interested in finding out from others in comments.

Interesting. I have the same issue on my 94. I also noticed when it’s really hot outside (I live in thePNW so it rarely happens) and I stop after driving awhile, there’s a “bumblebee hmmm” sound that comes from the canister.  Always a sound when removing the gas cap for fill-up. Toyota service said not to worry about it. Doesn’t seem to effect anything mechanically.

Auto Zone sells a replacement canister. Easy to install. Even I can do it.

Did you ever figure out why the tank was building pressure?

Is it true that if your canister gets clogged you can just use a Folgers can and some BBQ charcoal?

You did not check the purge valve,While the engine is running and the valve is open you should be able to blow with your mouth in the hose without any restriction.

What symptoms sent you down this path? I wonder if the charcoal becomes saturated with various impurities from the atmosphere and fuel vapors that cling to the carbon but don't release? Sort of like a dirty sponge that ya can't rinse. Therefore fresh charcoal could improve efficacy?