Hi all,

I'm trying to diagnose what seems to be a fuel issue on the GF's 2011 Cooper S. She hasn't really run into trouble starting the car from cold, but while driving she has had intermittent engine shutdowns followed by difficulty restarting. I'm seeing P0087 as well as 2C01, 2BF5, and 2BDD when I check the codes, so it seems likely to be a fuel problem of one kind or another.

This week I was finally able to watch the issue happen while I had an OBD tool connected with live data, and I saw the fuel rail pressure drop to around 16 psi before the engine stalled out.

Will the pressure get that low with a high-pressure fuel pump issue, or does that indicate an issue with the low-pressure fuel pump? Normal pressure supplied by the LPFP with the engine off seems to be more like 70 psi which makes me wonder if it's even possible to drop below that if it's a HPFP issue. She's had the HPFP replaced, but it's been enough miles that it could be due again. The LPFP is still factory. I'm just trying to find the right place to start.

Any additional diagnostics I should do before I start buying parts? (Also, anyone have a recommendation for a cheap but good replacement LPFP?)

Thanks for any help!

 

try to search for it on ebay !

 

I would have guessed HPFP at the start of your story, but since you saw the rail pressure drop, I'm leaning towards low pressure pump. With engine off, and key "On", you should expect 70-ish at the fuel rail. Then with engine started, you should see 800-1000psi at idle, and almost 2000psi with throttle application.

The part number is 16112755082. Here is an inexpensive option:
https://www.ecstuning.com/b-uro-part...112755082~uro/

 

Those are exactly the pressures I see, except when this problem presents itself and it drops to <20psi.

Is there a diagnostic test I can use to confirm, or is my first step just to go ahead and replace the LPFP? And should I do the fuel filter at the same time?