Fuel Vapor System

I had no choice, as all of my charcoal had magically disappeared between 1974 and last year. Since the can was in good condition, fixing it was easy. I used a good straight edge to mark a line about 3/4 of an inch above the bottom, so that I could cut the exterior above the seal, but where the can had multi-layers (hard to describe). Out popped the two steel screens. I put in a piece of A/C foam filter to keep the fish tank activated charcoal from rattling at the top and bottom, put the filter screens back in where they belonged, filled until I could just barely close the can, and then sealed it all with Permatex (or caulking would have worked).

Now, it's time for me to go check my vacuum routing and rubber diaphragm, especially since your description cleared up a lot of questions.

FWIW: The 1974 DJ5C had both the charcoal canister *and* the expansion tank just off the fuel tank. The expansion tank was fed by two vent lines from the fuel tank, and the output was routed to the charcoal.

 

I bought a used Jeep vapor canister like the one in the picture jpflat2a posted previously (and I re-posted here).

Timgr, you previously wrote: "Looking at the drawings that Jim posted, I would say that the drawing that says S6 (83/86) is wrong for your vehicle. As confirmed by my '74-80 parts book, Jeep used a 2-port canister for '74 and early '75. There is no reason to believe that the later canister, as shown in Jim's drawing, was used in '73, much less '72. My personal experience owning a factory-new '73 says it had the 2-port canister, conforming to my '74-80 book."

I assume you meant that this set up was not original to my vehicle and not that it wouldn't work for my vehicle. I plan to set it up exactly like this diagram, unless you don't think that is unwise.

My only remaining question is about the valve marked 3.051-7 in the diagram. These all seem like vacuum lines, so I don't know what a check valve would be doing there. If all the vacuum is running the same direction, and it's all air, not air and liquid, the valve seems pointless. Anyone know if it is necessary? If it is, what does it do? Maybe I can make another type of valve work (I assume this is not an available after market part).

 

It's the transmission controlled spark (TCS) vacuum switch. It has nothing to do with vapor recovery, other than being one of the emissions control devices. Jim pointed this out.