what the heck is this???

[turbo minivan]

on stock fuel lines there are 3 lines in my van, the feed, the return, and a small line that comes from a little plastic vent on the top of the tank and it goes to a big filter looking can in the front of the left wheel well under the hood. what is this? what does it do?

[slasky]

It is a vapor canister. It absorbs the gas fumes from the tank and then sends them into the engine to burn.

[mo' parts]

yea, its part of the emission system. most people unhook all that, but i got tired of the fumes from having it unhooked. may even get a little better gas mileage keeping it.

[OmniGuy123]

Quote:

Originally Posted by adam89shlbydayt yea, its part of the emission system. most people unhook all that, but i got tired of the fumes from having it unhooked. may even get a little better gas mileage keeping it.

I have not notices any decernable difference in GM on either of my cars in which I have disabled the vapor return.

[Phreakish]

it wont help GM - reason? well, there is NO way to know HOW MUCH fuel is going into, or out of the canister, and the purge solenoid just opens when the right schedule is reached in the computer, and its just burned - CA figures that its better to burn it than vent it into the atm. Because there isn't always a known amount of fuel in there, I dont see how the computer could schedule to use less fuel to make up for that being pulled from the canister.

The only downside is the fumeage you'll get when its gone... I havn't SEEN one on a newer car, but I"m not sure if they just put them somewhere else, anyone else know? for some reason I fathom that perhaps new cars just dont have them and have a better way of dealing with the 'issue'?

[clark]

your mpg will inprove with the vapor hooked up when the computer opens the valve and the vapor is pulled into the motor the computer will see the a/f richen and will back off the injector pulse so you will have the same a/f because of the vapor but not be injection as much fuel and because your using the vapers and not venting them u get better mpg,It wont be a vast inprovement but every bit helps

[Una]

I always unhook it from the engine, leave the canister in place to filter the fumes. Never get fuel smell in my car.