BMW 6-Series Power Loss & Stalling: Fuel System Issues?

I've got some experience with BMWs (some experience level). Had a similar issue with my 2004 BMW 3 series last year. The symptoms were almost identical to what you're describing, power loss, rough idle, and inconsistent performance. After a diagnostic scan, it turned out my high-pressure fuel pump was failing. Had it replaced at my regular workshop and it solved all those issues. The whole thing set me back about 1510 Euro, not cheap, but it had to be done. The symptoms you're describing sound very familiar to what I experienced. Before jumping to conclusions though, what's your engine type and mileage? That'd help me confirm if we're looking at the same issue. These problems can sometimes be related to other components depending on the specific engine variant. Keep us posted!

Hi! Thanks for sharing your experience! My 2006 6er has done 173741 KM and just had its service last month. You might be onto something with the fuel pump theory, the symptoms do match up pretty well with what you described. I'll get it checked out at the shop this week. The timing makes sense too since these pumps typically start acting up around this mileage. Really hoping it won't hit my wallet as hard as yours did though! Did you notice any other warning signs before your pump completely gave out? Like any weird noises or specific situations where the problems got worse? Appreciate the help.

Yeah, actually now that you mention warning signs, I remember some specific things before my pump completely failed. The issues were definitely more noticeable when the fuel tank was less than quarter full. The engine would start bucking and hesitating especially during acceleration, and it got worse in hot weather. Come to think of it, I also noticed a slight whining noise from the fuel tank area before things went south. It wasn't super obvious at first, but once I knew what to listen for, it was definitely there. My mechanic later told me that's a classic sign of a failing high-pressure fuel pump. With your mileage being pretty close to what mine was when it failed (I was around 168000 KM), I'd put money on it being the same issue. One tip though, make sure they check the fuel pressure with a proper diagnostic tool. My first mechanic just guessed and replaced the fuel filter, which didn't solve anything and just cost me extra cash. Keep us updated on what your mechanic finds. If it is the pump, maybe you can negotiate a better price than what I paid!

Hi! This is super helpful info! Now that you mention it, I've definitely noticed the problems getting worse when my tank's running low, and there's been this faint whining sound I've been ignoring. Guess I should've paid more attention to that! I'll make sure to tell my mechanic about the fuel pressure test, really don't want to waste money replacing parts that aren't the problem. Already called and booked it in for tomorrow morning. Going to specifically ask them to check the high-pressure fuel pump first, given all the symptoms match up. Thanks for saving me from potentially going down the wrong path with the fuel volume regulator. Having someone share their real experience with the same issue is way better than just guessing. I'll update the thread once I know what's what with my car. Really appreciate all your help!