Check engine lights drive me MAD... I'm not ocd but this is probably one of my qualities that could be considered borderline lol...anyway my jeep threw a po455 code(evap system gross leak) the other night and its no surprise I got cracking on it the next day after work. First I check my gas cap and that's what I find the entire way around the o ring. So I went straight to the dealer and got a oem cap.. Also checked all my evap lines from canister on back to the fuel tank the only questionable rubber fitting I found was this guy in the second picture. This is going directly into the evap canister under the Jeep. Got a 3" piece of hose, attached it, disconnected my battery to clear the code and so far about 20 miles later no light!. Let's hope it stays gone. Love the simplicity in some aspects of our xj's... There's something to be said for older vehicles

 

I hope your PO455 is solved. Can't see your pictures but I guess a bad seal on the gas cap and a rotten rubber elbow on the evap hose.
did you search for the many threads on this problem? I've had an ongoing struggle with this code for over 2 years.
I found that if I keep my fuel less than full, the code doesn't return after I clear it with my scanner. The evaporative test on my 98 Cherokee Classic only occurrs when the ECM (Engine Control Module) sees the fuel level between 1/4 and 3/4 tank. When I filled the tank previously the test failed when my fuel dropped to 3/4 tank. For 3 weeks now I've added $20 (about 6 gallons) everytime I drop to 3/8 tank. goes up to 3/4 tank or a little more and no check engine light.

I think some fuel is backing up into the evaporative line when I completely fill the tank and sits there until 3/4 tank and the evap test occurrs. Not sure about this and I wonder if anyone can take a guess at what's happening here?

I have my eye on the aftermarket 31 gallon aluminum tank but the $900 price has pushed that project into the future. It would rock to have 600 mile range on my Jeep.......Just think......New Mexico in 3 fill-ups.

Tank:
http://www.genright.com/ProductInfo....ductid=GST3003

See this thread:
https://www.cherokeeforum.com/f2/eva...-again-135159/

 

You know it's funny you talk about your fuel level The day beforei got the code I fueled up like normal. ..but I typed the tank off witch I've never done before.

 

And 600 miles to empty would be awesome... even more if we got it out of our 15 gallon tanks haha