What exactly does a charcol canister do anyways?

[Russell]

Hey guys!

None of my trucks less my 89 has ever had a charchol canister on them. I'm just wondering what exactly they do? I've got my charchol line from the tank's sending unit just blocked off with a breather right now, but my TPI has all of the equipment needed to run it, and I'm wondering if I should just toss one on. I have no problems running emissions systems so long as they don't take a lot of my power away (like one of those useless smog pumps) and actually perform a useful function.

 

[sandawgk5]

I think all it does is trap the vapors from the tank and hold them. When you start the engine the manifold pulls a vacuum on the tank and suck the vapors out and burns them. It is supposed to reduce the effects of gasoline vapors on the atmosphere what ever they are.

Ira

 

[Blue85]

Yeah, what he said. It is part of the "evaporative emissions" system, which keeps gas fumes from escaping. It doesn't do anything bad to your performance unless you have a vacuum leak in the system somewhere.

 

[Emmettology 101]

So say you have a rotted line to the tank.... You can cap the line on the tank without problems?

 

[dyeager535]

Actually you end up building pressure in the tank. I believe the later gas caps vent at something high like 16PSI. Try blowing through the tank side of your gas cap. That's what the tank has to overcome if you plug the vent and don't run a vented cap.

EVAP isn't simply an engine runs/dump it into intake/plenum/whatever function.

TPI uses an EVAP valve/solenoid, and the non-EFI stuff uses thermal/vacuum/timed setups to purge EVAP. Essentially though, it captures vapor while the vehicle is sitting allowing the tank to vent, and purges when the right conditions are met when the vehicle is running.

 

[Russell]

Cool, sounds like a good system to be installing then, I'll toss one onto the GMC later on I've got plenty of thin fuel line I can run along with the supply / return lines.

 

[dyeager535]

Yes, there really is no better way to vent the tank that I can see. I wish I wouldn't have pulled mine.

 

[highrlr]

Is this the can in front left corner of my engine bay?(if you were sitting in the engine bay looking towards the front). I see one of my lines going to it is broken, does it hurt to drive it for now like that till I get time to fix it?