Z4 Stalling Mystery: Fuel System Failure Signs

Had similar symptoms with my 2005 BMW Z3 last summer. Car was stalling at idle and running really rough. Turned out the fuel pump connector had corroded causing intermittent power supply issues to the pump. The connections were cleaned and sealed, and the pump harness needed replacement. Not a major repair, but definitely something that requires proper diagnosis. Initially thought it was the fuel pump itself, but my mechanic tested the pressure and found the connection was the culprit. The symptoms match what you're describing, rough idle, stalling, and fuel-related codes. The connector issue can mimic a failing fuel pump since it disrupts proper fuel delivery. Your Z4 is around the same age as my Z3 was when this happened, and these connection issues are pretty common in BMWs of this era. Would recommend getting it checked soon though, as driving with intermittent fuel supply isn't great for the engine.

Thanks for sharing your experience! That's really helpful as it sounds exactly like what I'm experiencing with my Z4. I'm going to have someone look at the fuel pump connections first before replacing any major parts. Just wondering, do you remember roughly how much you ended up paying for the repair? Also, has everything been running smoothly since you got it fixed? I want to make sure I'm prepared for what's ahead.

Hey there! Happy to give you an update on my repair experience. The whole thing ended up costing me 95 € to fix the faulty cable connections, which was honestly a relief since I was worried it might be something much more expensive like a complete fuel pump replacement. And you'll be glad to hear that since getting it sorted, my Z3 has been running like a dream! The mechanic discovered it was actually down to incorrect fuel composition messing with the system, along with those corroded connections we talked about earlier. Once they cleaned everything up and got the fuel mixture right, all those annoying symptoms, the rough running, stalling, everything, completely disappeared. It's now been several months since the repair, and I haven't had a single issue. The engine runs super smooth, even at idle, and that pesky check engine light hasn't shown its face again. Definitely worth getting it checked out, sounds like you might be dealing with something similar to what I had. Just make sure whoever looks at it checks those fuel pump connections thoroughly!

Thanks for all the details! I finally took my Z4 to a reputable mechanic yesterday. It turns out you were spot on, the main issue was corroded fuel pump connections, just like your case. The mechanic showed me the problem, and honestly, it looked pretty bad. The repair cost me about 120 € total, including cleaning the connections and replacing some worn-out parts. A bit more than what you paid, but still way better than having to replace the entire fuel pump. Got the car back today and what a difference! No more stalling, runs perfectly smooth at idle, and the check engine light is finally off. Such a relief it wasn't anything major. Really glad I asked here first, saved me from unnecessarily replacing expensive parts. Thanks again for steering me in the right direction with your experience!