There is a metal tube coming from the charcoal canister which is behind the passenger side headlight. Follow it to the carburetor. Disconnect the hose from the metal tube,and then put something in it. I used an old drill bit. Anything to plug it. The metal tube can be left open.

Now, test drive it. Is it fine? Great! You just plugged a leaky bowl vent valve. The result will be slightly more difficult hot starts, and sometimes dieseling. Carb rebuild kits don't include the valve, and they aren't available anywhere I know of.

Give it a shot, its very very very very common on the 2.6 with that carb