Griffter you are more than welcome to contradict me any time you want
i certainly dont know everything .. all i can ever do is give my opinion the same as everyone else .
i dont know the system 100 % but have figured most of it out and to be honest i was trying to bump this thread and get a few more comments so that perhaps we can figure out whats causeing the tank collapse .. Infrasilver has modified a pipe atm ...
So in my eyes we still havent got to the bottom of this .. and i would like to .
The carbon canister is indeed there to catch fuel vapours .. one for save the planet but mainly its a dam waste of a burnable fuel to just dump it.
Its just a canister with activated carbon granules as far as im aware .. fuel vapour will be collected in these granuals and when needed be drawn into the engine.
The part i was struggleing with is that dam pipe thats open to atmosphere .. you would think that this pipe would stop a tank collapse but the diaphram pipe had been replaced and thats the only part i can see that would block ANY air getting into the tank other than removeing the filler cap ...
yet it still collapsed .. this and Locosaki post above yours .. his was similar and the vent valve on the engine was causeing it makes me think that although this pipe is open perhaps it cant give the volumn of air to the tank that is needed .
As fuel is pumped out of the tank then air has to replace it from somewhere .
It may be a combination of this pipe and the valve on the engine that does it .. either way those are the bits that need checking .. we dont have a blockage but a restriction i feel .
Couple of images .. one is the american system but that is different to ours .. we have no pressure sensor or shut off valve ..
The other is the canister internals .. again we have no shut off valve there.