Mini Roadster Fuel Issue

Check engine light, rough idling, and reduced power on a Roadster? Sounds like a fuel issue for sure. Have you scanned the car for codes? What codes are you getting? Could be a faulty sensor throwing things off before condemning the high pressure pump. What kind of fuel economy are you seeing?

P0087 and pressure drops definitely point towards a fuel supply problem. While it could be a sensor issue, fluctuating pressure suggests the pump is struggling to deliver consistent fuel flow. Testing the pump properly usually requires specific tools and knowledge. I'd suggest getting a professional diagnosis to confirm before replacing the high pressure fuel pump. A bad pump will definitely affect the fuel regulator causing rough idling.

Yes, I scanned it and got a P0087 code indicating low fuel rail pressure. I also monitored the fuel pressure with my OBD reader and saw significant drops, especially at idle. I know the code points towards the fuel regulator, but I'm wondering if there is something else I should check before throwing parts at it. Is there any way to test the high pressure fuel pump without specialized equipment?

Just wanted to close the loop on this one. Turns out you were spot on. Took the Mini to a trusted mechanic and they confirmed the high pressure fuel pump was indeed the culprit, leading to a defective fuel regulator. Had the pump replaced, which sorted out the fuel injection issues, and the car is running smoothly again. Fuel economy is back to normal, and the check engine light is gone. Total damage was 1510€, but at least the problem is solved. Thanks for the help!