How a charcoal cannister works

I've seen this question a lot lately so here is an answer that should come up when you search. -Prior to whatever year the charcoal cannisters appeared, the gas tank vented to atmosphere. If you walked past a vented car on a hot summer day, you smelled gas fumes. To keep these fumes out of our air, the car makers figured out that activated charcoal (same as a fish tank filter) can absorb 100 times it's weight in gas fumes. So they ran a vent line from the gas tank to the canister and a line to the float bowl to capture and hold the fumes. When the motor starts, the fumes are drawn into the carb to be burned. That is why there is a filter on the bottom of the canister to flow fresh air over the charcoal and later cars have a solenoid to control the release. The gas cap that used to be vented, was now sealed so fumes cannot escape. This is a passive system that in no way affects the performance of the car.

Yes, if you can find one. Probably Rockauto would have it. If it is clean looking, no holes, and you can suck air freely through it, it is fine.The only car I needed to change it on was a 75' Matadore. It was clogged solid and dripping gas, which was a serperate issue. More often the filter gets a hole and charcoal falls out which lowers resistance and the cannister acts like a vacuum leak. If left alone it lasts a very long time without causing trouble.

Bill, Blake's idea sounds like a good one but I would place the plastic vent in the rubber line at the top of the gas tank and maybe even a little higher. Gas vapors are heavier than air and would not tend to escape unless they were under pressure like on a hot day.The Jeep uses a long hose from the axle up to the top of the engine compartment with that same plastic vent so it won't get water in it while off-roading. In the bad old days the factory just ran a vent line up and away from the tank and ended it with a curl, not unlike a sanitary pipe vent. As for the return line, the main reason the factory added it was to avoid vapor lock, especially on V-8 air conditioned cars. As the gas line passes the hot-as-hell front of the motor with hot air from the radiator being blown at it, the fuel boils and creats a bubble that will not let liquid fuel pass. By redirecting the excess fuel back to the gas tank, only fresh cool fuel is sent to the carb. Lots of cars came with only a supply line so it's no big deal to remove the return line and use a non-return fuel pump. Just don't try to use a return line pump without a return line as it will flood the carb and cause trouble. Vented gas caps are hard to find and wouldn't fit our screw-in type anyway. I guess a hole is just as good.