I own a 1985 cj7 that has very low miles on it due to it sitting for 10 plus years. I have been driving it now for the past four years. The problem is the evaporation cansister has not been working on it during this time. Which cause the vehicle to run lean at idle. So I thought I would just buy a new one. Well they are not available. Does any one know how to bypass this thing?

If you think the cannister is the problem pull the vac hose from it and plug it to check if that fixes the problem, if so, check the gas cap for air leaks. <img src="/forums/images/graemlins/smile.gif" alt="" />
Big Jim <img src="/forums/images/graemlins/pfft.gif" alt="" />

pop the hood, look at how many vacuum lines are under there, figure out how many feet you will need of each size, there is a general size for vacuum lines, then the rest of the tubes under there....

Go down to your local parts house and get as much as you figure you need, plus a couple of feet, and start replacing the lines. Never hurts to do this!

Following this, you can get charcoal evaporator canisters, or if nothing else, you can replace the filter for under $2.00. I've never done this, but they have changed what these things look like, and run about $55.00 for the canister and do the trick.

Now, like BigJim said, check vacuum lines, and also the fuel cap. sometimes there is not enough vacuum due to a leaky or vented fuel cap, and other times, there is too much vacuum back there, and ya have to pop the cap....

Now, then, what is your CJ doing or not doing that is leading you to think the canister isn't working????

There should be only 2 lines to the engine on that canister, the purge signal and the vent. Of these 2 only one is hooked up to vacuum, the purge line. It should be hooked up to ported vacuum, so it should not be effecting your idle. Why do you say that it is causing the engine to run lean? Have you artificially enriched it there?

Verify that the control circuit is functioning and that it is indeed hooked into ported vacuum.

I pinched off the main purge line on the charcol canister> (The second one from the left) and it changed the idle on my jeep made it run smoother. I was told by a mechanic that this is an indication of a bad evaporation canister. So how does the gas cap figure into this. <img src="/forums/images/graemlins/patriot.gif" alt="" />

As to what the jeep is doing it is running rough at idle. It has done this since I got the jeep running after sitting for 10 years. I have replace the carb. the air tubes and parts. and other related items and no change. The only way I can get it to run smooth is to pinch of the second line on the canister (The main purge line). There are four lines going to the canister and they are no longer available from the dealer or anyone else that I know.
<img src="/forums/images/graemlins/patriot.gif" alt="" />

How do I check for ported vacum. It should all be the way it came out of the factory as I bought the vehicle from the orginal owner with only 40000 miles on it. <img src="/forums/images/graemlins/confused.gif" alt="" /> <img src="/forums/images/graemlins/patriot.gif" alt="" />

If the idle is adjusted properly the PORTED vacuum line will NOT have vac in it at idle..
The result of this is, the canister cannot be "seen" by the engine at idle! So it cannot interfere with the amount of air available for ideling.
If you have the line to direct vacuum then the idle adjustment may not be able to compensate for that much air.
Big Jim <img src="/forums/images/graemlins/pfft.gif" alt="" />

Right Jim there should be no vacumum at idle. But, the valve that is supposed to remain closed at idle is not. i.e. causing a problem and the need for a new canister which no longer exists. So, is it possible to by pass this device. <img src="/forums/images/graemlins/confused.gif" alt="" />

Greg it seems you don't listen well! ONE OF THE PORTS ON THE CARB HAS NO VAC AT IDLE!! PUT THE CANNISTER ON THAT ONE!!
Please understand the cannister CANNOT cause idle problems when installed on the CORRECT vac line!!!
Big Jim <img src="/forums/images/graemlins/pfft.gif" alt="" />