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A year or so ago I pulled the fuel tank to repair the HVAC and when I pulled the vent off the top of the tank I noticed what appeared to be carbon in the lines. There’s no issue with how the car is running and the fuel filter should catch anything so I bought a new vent line valve #8 in the diagram and didn’t get around to installing it or addressing the carbon issue.
Before I drop $400+ on a new carbon canister, has anyone else had this issue? Was it a failed carbon canister?
The only symptom I have is a fuel smell in the frunk from time to time and every now and then I get positive pressure in the fuel tank which is noticed when I open the gas cap.
Hi JHG,
Before you "drop $400+ on a new carbon canister" . Consider removing it and see if you can recharge it with carbon.
Something like this: https://www.mgexp.com/article/rebuil...-canisters.326
Could save some considerable coin in the process.
Andy
Last edited by pp000830; May 13, 2026 at 10:15 PM.
I recently had this same thing. The charcoal canister filter membranes had failed. I found loose charcoal granules in the vent line near the gas tank and in the left rear wheelwell area under the charcoal canister.
I recently had this same thing. The charcoal canister flter membranes had failed. I found loose charcoal granules in the vent line near the gas tank and in the left rear wheelwell area under the charcoal canister.
Aside from replacing the canister, did you do anything else? I don’t have a diagram handy for this, did you find carbon in any other areas that needed to be cleaned or blown out?
Blew out the vent line at the roll-over valve (# 8 in diagram) by mouth, back to the charcoal canister. Got maybe a teaspoon of charcoal granules out of that line.
Vacuumed the granules out of the wheel well area. Replaced the canister with new one. Old canister was leaking charcoal from upper vent "Tank" & lower air inlet "Luft" nozzles. Nozzles are labled on canister, "Tank", "Motor", and "Luft" (for atmosphere) IIRC. Motor nozzle was not leaking in my case, could still see intact filter membrane inside.
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Carbon canister question
