"Check gas cap" purgatory

[Captain_Ron]

A little follow-up. After I had replaced all of the recommended EVAP parts and still had CEL, I finally took the truck to my trusted local mechanic. He dropped the gas tank and there was the answer. Mice! Mice (or squirrels) had chewed through two of the hoses that sit on top of the fuel tank that carry the vapors back and forth. Lord knows what those hoses are for, just more emissions garbage.

No way in a million years would I have found that since I could not see that part of the tank. He repaired the hoses, threw some mouse bait in there for good measure, and **** - no more CEL's! Just goes to show, always expect the unexpected!

 

[Daniel Ortiz]

Gentlemen,

I finally had the "Check Gas Cap" light come on. Luckily I only fired the parts cannon ONCE on the gas cap (replaced with Mopar) before I decided to start testing stuff. Thank you @GTyankee for your post showing all the ways to test the evap system components. Much appreciated.

The purge valve on the engine was working correctly: it stayed closed without power, and opened with 12 V across the terminals.

I pulled the ESIM on the tank and checked for continuity. It should close the circuit with positive pressure on the white outlet or negative pressure on the black outlet, but it didn't, so bingo. It was the ESIM.

I bought a Mopar one, but it didn't come with an o-ring, which I saw some Dorman ones did. The Youtube videos I saw showed the factory ESIM came with a rubber gasket ring, but my old one didn't seem to have one, and when I felt the canister end with my fingers, it didn't seem to have one either. So I took a picture to see better:



!!!

I'd been driving around with that yellow o-ring right there for a week at least. Whew! I cleaned it up and It's now soaking in some AT-205 re-seal to give it some new life. However, can anyone else confirm that this was the o-ring that came with the ESIM from the factory? I presume mine is, because you can even see some yellow remnants on the canister, but I thought I'd ask you all anyway. It doesn't fit very snugly on the new ESIM, but looking at this photo from the side, I suppose it is just about right for the interlocking tabs on the canister side to fit in there.



Anyway, I'll reply once I get it buttoned up and let you all know if it cleared the codes and lights.

Keep Ramming!

 

[Daniel Ortiz]

The codes are clear! It took about three days of drive cycles. It wouldn't let me delete either. I guess its a permanent code.

So that o-ring was indeed the one from factory. The yellow paint rubbed off from its soak in the AT-205 Re-Seal. No matter. It still fit snugly in the canister end:



After that, the ESIM fit in no problem and clicked into place. I hooked up the hose and electrical connection and that was that.



Then it was three days of that dumb gas cap light before it turned off. Another repair in the books!