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Ignition question here for a 1990 BMW e32 735il with an M30…

Customer Question
Good morning. Ignition question here for...
Good morning.
Ignition question here for a 1990 BMW e32 735il with an M30 3.5L straight six engine.Parking it one day, it wouldn't restart. Starter motor turned fine, electrics fine, sounded like fuel starvation.So.
To date, and with three other mechanics and countless trips to various BMW E32 forums:Replaced:
1) fuel pump (three times)
2) fuel filter (yes, exhaust smells rich on start)
3) fuel pump relay
4) main relay
5) spark plugs
6) cap and rotor
7) spark wires
8) main coil
9) crank position sensor
10) ECM (twice)
11) checked the fusable links - yes, power going to the ECM, all the relays.
12) coil tester reveals nothing coming out of the coil. Will get the proper oscilloscope to monitor that after
13) just ordered another crank position sensor on the premise that the one replaced in 9) might be faulty, and not let the ECM know the motor's turning over at start.So.
The electrics work okay.
Definitely a spark to the system when tested directly, but no main coil trigger signal coming out of the ECU. All pathways to and from the ECU tested cable-wise and seem to check out.This above done by certified BMW mechanics.We're out of ideas here.
Anybody with this kind of experience and knowledge on the E32?Thanks!
Submitted: 10 months ago.Category: BMW
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Answered in 1 minute by:
9/26/2017
BMW Mechanic: Steve, BMW Expert replied 10 months ago
Steve
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BMW Mechanic: Steve, BMW Expert replied 10 months ago

so the ecm seems fine and powered other than it is not sending a spark signal?

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Customer reply replied 10 months ago
Seems like it. just waiting to change out the crank position sensor, which seems to send the signal that makes the ECM turn everything on ignition and fuel wise. And, of course, turn everything off in the event of, for instance, a crash.
BMW Mechanic: Steve, BMW Expert replied 10 months ago

Please do not forget to click a positive rating as this is the only way I receive credit for my answer, thank you

I would replace the crank sensor again and if the issue persists, it points to the ecm as the likely culprit.

Please let me know if you have further questions. Please do not forget to click a positive rating as this is the only way I receive credit for my answer, thank you. Best wishes with your vehicle...

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Customer reply replied 10 months ago
Except that I already replaced the ECM twice... :)
I'll do the crank sensor tomorrow morning and let you know how it went.
And I have the BMW e32 factory manual with comprehensive wiring diagrams already - otherwise I wouldn't know which pins on the ECU did what!
Best
Chris
BMW Mechanic: Steve, BMW Expert replied 10 months ago
ok good luck with the crank sensor
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