Infiniti M Hybrid Stalling & Smoking: Help Needed

I experienced similar symptoms with my 2014 Infiniti Q50 Hybrid last year. Initially thought it was the fuel pump too, but it turned out to be a damaged wiring harness that was affecting multiple systems. The connections had corroded over time, causing intermittent electrical issues that messed with the engine management system. The main symptoms were exactly like yours power loss, rough idling, and black smoke. My car would sometimes jerk while driving, especially during acceleration. The worst part was when it would unusually stall at traffic lights. Took it to the dealer, and they found several damaged wires in the main engine harness. Some connectors were completely shot. They had to replace the entire harness assembly. It was a serious job that took a couple of days to fix, but it completely resolved all the symptoms. The car's been running perfectly since then. Given your symptoms, I'd strongly suggest getting the electrical system checked first before replacing any mechanical parts. These issues can be tricky to diagnose without proper diagnostic tools.

Thanks for sharing your experience with the wiring harness! My symptoms do sound really similar to what you had. Quick question do you remember roughly how much the repair set you back? Also, has everything been running smoothly since then, or have you noticed any other quirks pop up? Just trying to get an idea of what I might be looking at cost-wise and if I should expect any follow-up issues. Cheers!

Hey there! Glad to help follow up on this. Yeah, I did get it sorted out turned out you were right about it being electrical. Had the car checked out and they found it was indeed the wiring harness that was causing all the drama. Got it fixed about 8 months ago and honestly, it's been running like a dream since then! Not a single problem. The repair was actually way cheaper than I initially feared ended up being 95€ to fix the faulty wiring harness and connectors. Much better than what I was expecting, especially since I was worried it might be the fuel pump (which would've cost way more!). The mechanic found the fuel pump was actually working fine it was just the dodgy wiring that was making it seem like a pump issue. Once they sorted out the electrical connections, all those symptoms the stalling, black smoke, jerking completely disappeared. If your symptoms are matching what I had, definitely get those electrics checked out first. Could save you a bunch of money compared to replacing parts that might actually be fine!

Thanks so much for all the details! Just got back from my mechanic yesterday, and you were spot on it was the wiring harness causing all the trouble. What a relief it wasn't the fuel pump! The repair cost me about 110€, a bit more than yours but still way better than what I was expecting. My mechanic found some pretty corroded connections, fixed them up, and replaced a few damaged wires. Took them about half a day to sort everything out. Took the car for a good spin after picking it up, and wow, what a difference! No more stalling, black smoke's gone, and it's running super smooth now. Even my gas mileage has improved. Feels like I got my old car back! Really appreciate everyone's help here saved me from potentially spending way more on unnecessary repairs. And found myself a new, more trustworthy mechanic in the process. Win-win! Thanks again!