"Fuel System Malfunction" HPFP, Injectors, or LPFP?

Aceway · 01-30-2021, 07:54 PM

Hi all, my M5 is at 73k miles and I got a "fuel system malfunction" warning. Tried clearing all codes with no change. I ran a diagnostics and only one fault shows up under fuel system. After cold start, the rpms bounce up and down. Whenever the car wakes up, what sounds like the lpfp running will start and will not turn off unless I cycle the ignition.

My guess right now is hpfp because from my understanding injectors will throw a bunch of codes when they fail. Maybe the ekps module? I don't really want to throw parts at this car since it adds up really quick. Any help is appreciated.

M5Rick · 01-31-2021, 05:02 AM

Clean the MAF's first if you haven't done so already and check the 02 sensors.

technician117 · 01-31-2021, 07:09 AM

I couldn't hear anything on your video, but are you saying that the LPFP stays running with KOEO? It might not be building enough pressure. I'm only speculating, but I think when it primes, it shuts off when it reaches a certain pressure. So if it can't reach the target pressure, maybe it keeps trying.

01-30-2021, 07:54 PM	#1
Aceway Captain 455 Rep 875 Posts Drives: E82 135i / F25 28i Join Date: Feb 2018 Location: SoCal iTrader: (2)	Hi all, my M5 is at 73k miles and I got a "fuel system malfunction" warning. Tried clearing all codes with no change. I ran a diagnostics and only one fault shows up under fuel system. After cold start, the rpms bounce up and down. Whenever the car wakes up, what sounds like the lpfp running will start and will not turn off unless I cycle the ignition. My guess right now is hpfp because from my understanding injectors will throw a bunch of codes when they fail. Maybe the ekps module? I don't really want to throw parts at this car since it adds up really quick. Any help is appreciated. Attached Images
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01-31-2021, 05:02 AM	#2
M5Rick General 60061 Rep 19,546 Posts Drives: M5 F10 DCT Gunmetal Join Date: Aug 2018 Location: Southern England iTrader: (0)	Clean the MAF's first if you haven't done so already and check the 02 sensors.
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01-31-2021, 07:09 AM	#3
technician117 Captain 251 Rep 606 Posts Drives: 2000 M5, 2001 M5, 2013 M5 6MT Join Date: Jul 2018 Location: Buffalo iTrader: (1) Garage List 1990 BMW M5 [0.00] 2000 BMW M5 [0.00] 2013 BMW M5 [0.00]	I couldn't hear anything on your video, but are you saying that the LPFP stays running with KOEO? It might not be building enough pressure. I'm only speculating, but I think when it primes, it shuts off when it reaches a certain pressure. So if it can't reach the target pressure, maybe it keeps trying.
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