BMW M3 Fuel Vent Issue Causing Multiple Symptoms?

Hey there! I experienced almost identical symptoms with my 2020 BMW M4 last winter. The fuel smell and stalling were definitely concerning. Turned out to be a defective activated charcoal filter in the EVAP system. When it fails, it can't properly handle fuel vapors, leading to those exact issues you're describing. Got it fixed at a shop specializing in German cars. They had to replace the entire charcoal canister assembly and purge valve. Not a hugely complex repair, but it needs proper diagnostic equipment to confirm. Don't ignore it though, a faulty EVAP system can lead to bigger problems if left unchecked. Best to have it checked by a certified BMW technician who can properly diagnose and fix the evaporative emission system. The symptoms match exactly what I dealt with, and it's pretty common in these models. Good luck with the repair.

Thanks for sharing your experience! This is super helpful since I've been worried about the repair complexity. The symptoms you described match mine perfectly, and I'm relieved to hear it's likely just the charcoal canister system. Would you mind sharing what the repair cost you? Also curious if you've had any similar issues pop up since getting it fixed? My M3 has been reliable otherwise, but this fuel smell is getting pretty annoying.

Hey again! Happy to give you an update! After getting my M4 fixed, I haven't had a single issue with fuel smells or stalling, it's running perfectly. The repair set me back 275 € for replacing the faulty activated charcoal filter, but honestly, it was worth every penny. The fuel tank ventilation system is working like a charm now. My car's been super reliable since then, no problems whatsoever. The mechanic told me these filters typically last quite a while, so you probably won't have to worry about this happening again anytime soon. Mine's been solid for about a year now. Just make sure you get it sorted soon though, driving around with that nasty fuel smell isn't fun, and you definitely don't want any fuel vapor issues turning into something bigger. The fix itself was pretty straightforward, took them just a few hours to complete. Let me know if you need any other info, always happy to help a fellow BMW owner!

Thanks for all the details! Just wanted to update, I bit the bullet and took it to a BMW specialist yesterday. You were spot on about the charcoal canister! Got it replaced along with the purge valve, and the difference is like night and day. No more fuel smells, and the engine runs smooth as butter at idle. Cost was pretty similar to what you paid, and the whole thing took about three hours. The mechanic was great, really took the time to explain everything and even showed me the old parts. Pretty gross how gunked up they were! Got to say, I'm kicking myself for not doing this sooner. Been driving around with that annoying fuel smell for weeks when it could've been fixed in just one morning. Really appreciate your help pointing me in the right direction. The M3's back to being the dream car it should be! Think I've finally found a trustworthy mechanic too, such a relief after my last disappointing experience. Thanks again for all your help!