E92 M3 EKP / Fuel pump diagnosis

[SkinnedKnuckles]

Hi all,

Help required as the car is currently stranded - thanks in advance!

2008 (Feb) E92 M3 RHD, ~170k kms.
Recent oil service, new battery and plugs.

Out of nowhere yesterday, the car idled roughly when started, then hesitated for a couple hundred metres before about to die. Stopped, restarted, it ran for a few seconds then died. Same again. Then wouldn't fire at all. Just crank crank crank... Cranky!

I used Carly adapter/app to pull codes; it showed fault code: 0027E6 "no EKP control".
When I click "details", it says:
- Duty cycle (in German) EKP module: 0.00%
- Electricity demand fuel pump: 0.00A
- Engine speed: 0.00 U/min
- Voltage KL30 on EKP module: 30976.00V

No other fuel pump, sensor or pressure codes showing. Cleared codes, retested multiple times, same outcome.

Google was not much help at all; there appears to be nothing about this particular code (perhaps the code is not quite "correct"?) and very little info out there (or on this forum) on this M3 pump and control module diagnosis/issues.
Being a three-phase pump, my understanding is that it's hard to diagnose input signal issues or operability without a scope or other fancy gear. My simple multimeter doesn't seem to be much use.

I did some investigation and measurement with what I had; here is what I found:

- ALL fuses behind glovebox seem ok (removed and checked the key culprits, checked continuity in place on all fuses also)
- EKP module input Red wire shows circa battery voltage (12.15V)
- EKP module input Brown wire showed continuity with known ground
- EKP module output pins (with the cable to the fuel pump unplugged):
(1) (pin that goes to red wire): 0V while cranking
(2) Yellow: 0V then 1.3V while cranking
(3) Brown: 1.1V while cranking
(4) Black: 1.4V while cranking
[Voltage at pins 2/3/4 dropped back to zero a few seconds after cranking stopped (after I pushed stop/start button a second time to stop the cranking after no-start), coinciding with that strange single "clunk/clink" sound that usually comes from the "engine" about 5 seconds after engine shutdown; was never sure what that was, perhaps a key relay?!]
- Removed EKP module from car, removed cover and inspected; no clear visual signs of damage (was kinda hoping to see a burnt board or something obvious!)
- Exposed top of fuel pump (removed rear seat cushion and cover plate); removed input connector (coming from EKP module);
...measured continuity between the 4 pins on the top of the pump unit:
> There was continuity between the pins (any two) that correspond with the Red, Brown and Yellow input wires (but not with the pin that corresponds wth the Black wire);
..measured the resistance between the 4 pins:
> Blk-Red = ~130 Ohms
> Blk-Brn = ~130 Ohms
> Blk-Yel = ~130 Ohms
> Any combination of two pins corresponding to the Red/Brn/Yel wires = around 0.7 Ohms
(not sure if the above was useful yet, just working with what I had)
- Reconnected the plug to the fuel pump, back-probed the Yellow wire while cranking; started at 0V then it measured 1.3V while cranking, and again it held at 1.3V after cranking stopped, for a few seconds, until the familiar single clunk/clink from the "engine", where it dropped back to zero.
(in no cases above did the engine fire up btw)
- Unplugged fuel pressure sensor connector under the bonnet behind the airbox (this supposedly should trigger the EKP to tell the pump to run at full output?); again it just cranked but no start..

During the cranking tests above, I held one hand on the top of the pump to feel for pump operation, but there was no noticeable sound or vibration... It does not seem to be running at all. I listened carefully when unlocking the car and when turning the ignition on (as some suggested it may prime then); but no pump sound was apparent..

And yes, I realise that measuring the voltage from the EKP to the pump is not ideal (perhaps not even useful?) due to it being a 3-phase pump, but it does suggest to me that the EKP is indeed signalling the pump to operate (but I can't confirm if this signal is "correct" or not without a scope or more fancy diagnostic gear..)

So, a few key questions arise:
1) Fault code apparently suggests EKP issue, but could this be a pump failure instead? If so, why no fuel pump codes or "downstream" codes re pressure etc?
2) What can be made, if anything, of the measurements noted above at the EKP module and at the fuel pump? Is the EKP perhaps working properly?
3) Is there another way to test the pump, without fancier diagnostic gear?
4) Where TF is the Schrader valve on the fuel "rail" in the engine bay?! I can't actually confirm zero fuel pressure to confirm pump is indeed not running?!
5) What else can be done to identify the true issue without towing the car to a mechanic?
6) Is there any risk in swapping out the EKP module with a known-good unit for the sake of testing if this is the culprit? Could this damage the borrowed EKP module somehow? AFAIK there is NO need to reprogram these modules for the M3 (as per BMW service doc pdf found online), so this seems like a good idea if I can track one down from a running car..


I'm leaning towards it being a suddenly-dead fuel pump, but it would be nice to confirm this before shelling out for a new one. It's a pity I can't simply hook up 12V to test it like the "old" ones! Hmmm....


Anyone have any ideas or suggestions on how to narrow down the diagnosis without access to fancy test gear? Really trying to avoid wasting $$$ with simply towing to the dealer for "fix", before exhausting other avenues! (note- the dealer wants over $1000 here in OZ just for the EKP module; approx twice the cost of what it is in the US, so I suspect they'll want ++AUD$1000 for a fuel pump too, considering it is more than the EKP module over there...crazy)...add labour at $220+/hr and you see why I want to try to sort it out myself if possible!

Many thanks in advance for any and all advice/tips/help!

Cheers

[askjeeves]

I went through this on two bmws that weren't m3s (335 and 535), and this is my anecdotal experience. Both had codes for ekp. 335 would crank and not run at all. I tried replacing the ekp module first, which didn't fix it. It was a dead fuel pump. 535 would run for 20-30 minutes and then die. The ekp was overheating and failing. From what I read that's pretty common vs the ekp module completely dying suddenly. If you had to throw a part at the car as a guess, I'd try the fuel pump first. If you have INPA you might be able to trigger the fuel pump (i figured out how to do that the second time around which helped confirm the ekp fault in the 535).