BMW 6 Diesel Won't Start: Fuel Pump Failure or More?

Hey there! I've got some experience working on BMWs. Actually, I dealt with very similar symptoms on my 2011 BMW 5 diesel a couple years back. Like you, I first thought it was the fuel pump, but turned out it was just a faulty wiring connection to the fuel pressure sensor. My trusted mechanic found that the cable connection had corroded over time. They cleaned and fixed the connection, and also checked the entire fuel system just to be safe. Total bill was 95 Euro and it's been running smoothly since then. Before jumping to conclusions though, could you share: Any error codes you're getting? When did these symptoms first start? Does it happen more when the engine is cold or warm? This info would help identify if you're dealing with the same issue I had. The BMW 6 and 5 share quite a few components, so I might be able to point you in the right direction.

Thanks for your detailed response! I just hit 113984 KM and had my last service about 2 months ago. The symptoms started about a week ago, mostly when the engine is cold, especially in the mornings. I'm getting error code P0087 (fuel rail/system pressure too low). It's interesting that you mention the wiring issue, I hadn't considered that. I'll definitely get those connections checked before replacing the entire fuel pump. Did you notice if the symptoms got worse gradually or did they just appear suddenly? I'm trying to figure out if I can safely drive it to the mechanic or if I should have it towed.

Hey again! Happy to help further with this. Yeah, in my case, the symptoms definitely came on gradually over a couple of weeks. Started with occasional rough idles in the morning, then got worse until it was happening pretty much every time I started the car. That P0087 code is exactly what I got too! The funny thing is, I actually drove mine to work for about a week before getting it checked out (probably not the smartest move, looking back). But seeing that you're experiencing almost identical symptoms to what I had, including the cold start issues, I'm even more convinced it could be that wiring connection I mentioned. Just to put your mind at ease about driving it, I managed to get mine to the mechanic without any issues, but I kept the revs steady and avoided any hard acceleration. If you're within a reasonable distance from your mechanic, you should be fine to drive it carefully. Though if you're worried, there's no harm in getting it towed, better safe than sorry with these BMWs! Quick tip from my experience, once they fix it, have them document exactly where that corroded connection was. I keep a little maintenance diary now, and it's been super helpful for tracking these kinds of issues. The whole sensor/wiring system in these cars can be a bit finicky. Let me know how it goes, I'm genuinely curious if it turns out to be the same issue!

Thanks so much for all the detailed info, this has been really helpful! I feel much better knowing you drove yours with similar symptoms. Since I'm only about 10 minutes from my regular mechanic, I think I'll risk driving it there tomorrow morning, but I'll definitely take it easy on the way. Your maintenance diary idea is brilliant, I'm going to start one of those myself. It's crazy how something as simple as a corroded wire connection can cause so many issues. I've already called my mechanic and mentioned what you said about the wiring and sensor connections. He agreed it's worth checking that first before jumping into any expensive fuel pump replacements. I'll definitely let you know what they find, really appreciate you taking the time to share your experience. It's saved me a lot of worry and potentially saved my wallet too! Thanks again for all your help.