E350 Popping noise at idle from trunk area
 

Sometimes when I come to a stop I hear a light popping noise coming from what I think is the fuel filler area. I suspect it has something to do with the tank venting or evap system. Anybody know what is causing it. The dealer is unable to reproduce it. Which is somewhat understandable as it doesn't happen all the time.

Is it possible its the locking mechanism for fuel filler door?

First time I had this complaint, it took me forever to figure out what it was.

It's the shutoff valve on the charcoal canister thats located in the right rear wheel well. Its normal.

First of all thank you so much for replying. I have been living with this since I bought the car last March. What does this part do exactly? Could I disable it temporarily to confirm that the noise goes away when I do?

Not sure what you mean when you say its normal, I've never driven a car that does that and frankly it doesn't meet with my expectations of how the car should sound idling at a stop light. I mean it's not that bad but the car is a late model Mercedes. Are you saying that even if it was replaced with a new one it would make the same sound? And is there not an improved part?
Maybe the sound of the shut off valve is normal but how often it is being triggered isn't. Do you know what triggers it? Could another sensor be bad?

Again thanks for the reply I was hoping an experienced tech would respond.

They finally replaced the canister and the noise is gone. Wasn't normal

One of the dead bodies you are hauling around is not so dead, and wants out.

Haha....good one scott

Old one

OK, so you're aging dead bodies back there and suspect it could be the old one. Start with that guy.