Euro 850i (1992) cranks, doesn't start (no spark, no fuel)

[todor]

I'm gonna need some help from the experts here. My 01/92 build date 850i (manual) was running/driving beautifully until one day it just wouldn't start (I had driven it just a few days before that and hadn't changed anything in-between, and this was months after the last major maintenance where the intake manifolds and valve covers were off). Then over the next few days it would start intermittently but most times would just crank and not start. Still doesn't start. Here's the relevant info, please let me know what I should check or try next:

• No spark (tested with an inline tester, on both banks).
• Spark plugs were NGK ZFR5F, which is apparently the wrong type for this engine, even though it was running fine with them for at least 1k km; so I just replaced them with new NGK BKR6EK, but that didn't change anything.
• Fuel pumps don't run when cranking; they do run when I jump the fuel pump relays, i.e. pumps are fine. There is fuel in the tank.
• Fuel injectors were refurbished a few hundred km ago, should be fine (and plus, the engine doesn't sound like it "wants to start" as it would if there were spark and SOME fuel)
• Fuel pump and DME relays tested, they're fine
• Fuel pump relays don't get the signal to turn on from the ECUs (voltage difference between terminals 85 & 86 is zero); actually, when the ignition is on, it's not zero - it's about 1.5V. Could this indicate some sort of ground connection issue?
• Engine ground strap is fine, engine ground has continuity with chassis ground.
• Distributor rotor and cap are almost new (Beru); still, I took them out just now to inspect and they look fine, nothing is burned or unusual.
• Ignition coils are getting 12V at both terminals when the ignition is on (is this normal?)
• Crank position sensors are almost new (but not OEM - Vemo brand), and they measure about 540 ohms between pins 1 & 2. Car ran fine with them for a few years and 1k kilometers.
• I swapped the crankshaft position sensors with the old OEM ones (which were fine, they had been replaced preventatively, and still measure the right resistance between pins 1 & 2) and the engine did start!!! but only once. After I shut it off and tried to restart it - again, just crank, no start. I also had a used set of original CPSs from my other E31, so I tried those as well, and sometimes after a change of CPS the engine would start, sometimes for multiple starts, but eventually would not start anymore.
• Disconnecting the battery for a minute does usually cause the engine to start afterwards, but again only once or twice before it goes back to just cranking on the 2nd/3rd/4th attempt.
• The EML and DMEs are getting power at the right pins in their connectors (as per electrical diagrams)
• I swapped in the EML computer from my other E31 for a test (it's a CSi but should be compatible, at least to start the engine); still no start
• I swapped DME 1 with DME 2, no change.
• I swapped the ignition coils with my old ones (which were fine, replaced preventatively), no change.
• Voltage seems to be consistent, so the main fusible links at the battery should be fine. Haven't checked them physically though.
• I've tried locking & unlocking the car with the infrared remote and with the key a few times, no change.
• It's a Euro-market car, so there's no "check engine" light and no "stomp test" to get fault codes.

So I'm kind of at a loss here... any ideas what to try next? Is there any particular pin in the DMEs or the EML that gets a signal from the alarm/immobilizer and is it possible to check it? Is there an easy way to see if the coils are firing at all (to exclude a distributor or spark plug wire issue)? Are there any issues that would cause the DMEs or EML to detect "errors" while the engine is running and therefore not want to start the next time? I'm asking this because disconnecting the batteries does seem to "reset" the situation and the engine does start once or twice.
Thanks in advance!

[LappingLuke]

Fusible links can look ok and "test" okay but be mostly broken and cause a no start.

[dragon850]

Fusible links for sure.... they look ok but are cracked.

2nd possibility DWA is acting up, cartoonz also got an euro car with roll over sensor started... maybe he can chime in.

[todor]

I checked one of the fusible links, both look fine and measure fine but I'll replace them just in case. Will have to be in a few days though. I'll report back, however I doubt that's it, given that I can consistently start the engine successfully (once or twice) after disconnecting and reconnecting the batteries. The only way this could be caused by fusible links is if the ECUs are measuring the voltage or power that they're getting (or that the ignition components are getting?) and then recording an error which causes them not to start the next time. And when I disconnect/reconnect that error is erased, which allows the engine to start again once or twice. Does that sound possible?

[LappingLuke]

Don't overthink it.