I've been dealing with this issue for years so bear with me, this might get long.

I have a '09 Cooper S with ~100000km on it. I bought it used in the winter of '11 with 26000km on it and instantly was confronted with the cold start issue. My issue manifests at about -5°C (23°F) and is always the same, it cranks and sort of fires a few times with a bit of a chugging (feels like only a few cylinders are firing) then stalls and refuses to fire until I warm the engine bay up with a heater. Pumping the throttle at any stage of the start procedure does nothing, like the ECU is ignoring the input. No codes ever show up and I don't get a check engine light.

Mini Canada replaced the HPFP under warranty, and also installed a cold weather intake and the throttle body under a TSB. The car was reliable for a few winters but started acting the same way intermittently in '14. Unfortunately the car is only willing to fail when it's at home or at work and performs perfectly when taken to Mini or my local Mini/BMW expert, so Mini isn't up for replacing the pump. Frustratingly, I've had it towed to Mini after days of not starting only to have it fire up perfectly when it arrived.

At the suggestion of various mechanics I've replaced the temperature sensor, had a walnut blast, installed a catch can (god knows why), cleaned the injectors, cleaned the MAF sensor, replaced the spark plugs, and replaced two suspect coil packs. I also bought an OBDII reader and have recently been watching the temperatures and fuel rail pressure and I think things are pointing directly to the HPFP.

When it will start the pressure in the off position will be ~50-80psi. When I begin to crank it goes up to ~300psi, and when it catches it goes up to ~800psi. Spirited driving will get me to 1300psi and above.

When it won't start the fuel pressure never goes above 80psi.

Further, if it won't start I can take a hair dryer and blow hot air on the HPFP for a few minutes and it will then start with enthusiasm and run perfectly until the next morning. I don't get any of the hesitation issues some people get under strong acceleration, or any other obvious signs of a failing fuel pump. I suspect, but can't confirm, that there is something in the pump that is getting stuck and letting the high pressure bypass, and it gets unstuck with a bit of a warm up.

Should I just replace the pump, and if so, where can I find one for less than a C$1000? I keep reading that people find them for under US$500, but the links always turn up pumps for much more. Insights for other causes of this issue are welcome.

 

 

I just replaced my HPFP for the same issue you are describing, SX.
I got the $380 OSIAS pump that Bimmerdude recommends, off Ebay, https://www.ebay.com/itm/332348282777
So far, so good.
Make sure you also replace the 3 mounting bolts when you replace the pump.
It is also recommended to change the high pressure fuel line when replacing the pump.
I replaced both the high pressure and low pressure fuel lines when I did my pump, as well as a few other things.

My post for that is here if you want to check it out.
https://www.northamericanmotoring.co...lp-please.html