Colored hoses, Are they still available? Or has anyone tried dying a hose? Options

[TonyA]

Maybe i ma crazy but are these available anywhere, or has anyone ever attempted to bleach and dye a hose?

[wonkipop]

re mr sb's thoughts on emissions engineering/workings of the cannister.

its a reasonable take.

there are other explanations i have heard out there as well that make it trickier to really understand.

most descriptions talk about the fan line pushing, or being a pressure line and the air cleaner line being a suction line.
but i have also heard the fan line described as providing negative pressure. in which case the fan line (engine running) would be being used to suck fumes through the body of the charcoal the full length/depth of the charcoal from the smaller vapor line. while the suction line from the throttle would also be drawing it out to burn it. its possible the fan could be drawing air down the line as much as it could be pushing air, it just depends exactly where that line is tapped off the fan housing. i'm not really sure what the type 4 fan housing blower bleed line provides. however the interior of the cannister is interesting because usually the small vapor line extends well inside the cannister as a tube whereas the other lines connect more or less near the surface of the cannister.

i am also aware that sometime during the mid 70s porsche reversed the hookup of the fan and aircleaner lines in 911s. they ran a similar kind of charcoal "passive" system in that model - though some variations might have had a switched mechanical valve in addition.

but there is only so much you really want to know about these systems other than you have it correctly plumbed for the model/year you have?

they are interesting in the sense that this simple device knocked out roughly 50% of the hydrocarbon emissions from cars in one move without affecting engine performance.

what i am inclined to think is that the change was prompted by learning that if the charcoal became saturated due to too much urban driving and not enough long distance driving and purging then one or the other of these connecting hoses (fan bleed or aircleaner line) was the weak link that let fumes escape into the atmosphere. changing the configuration of the hoses might have given the charcoal greater capacity before the leak out occurred. in the vw system which the 914 has there is no mechanical valve.
the charcoal is the valve. but.....i'm still just guessing because i do not fully understand it....