Stumped - 325i not starting

[Ollie_bwoii]

Model - 325i.
Year - 1987
Engine - M20B25 High comp.
Management - Motronic 1.0, '073' ECU

I'm a bit stumped as to what is my problem here, so I'll run through what happened, and what I've done, to try and give a better understanding.

My 325i will not start, it just keeps cranking. Checked for fuel, which is present. Checked for spark at the plugs, nothing visible. Checked for a spark before the distributer, and its very weak, but present.

Therefore, my problem is before the distributer.

So I tried a known good king lead. No change.
Tested the coil, which tallied up as being fine, but thought I've got a known working one, so tried that. No change.
Tested the wiring to the coil, which was fine, and confirmed multimeter readings with another one of my BMW's.
On the off chance I Tested the ignition switch, and tried to start the car via the diagnostic socket. No change.
So, my thought's then made me think ECU, as its got an early '073' item. So swapped in a 'working on removal' used item from a trader. No change again.

I'm pretty darn stumped now, so thought it was worth asking on here, to see if anyone else had any ideas.

Many thanks for reading,

Ollie.

[Ollie_bwoii]

Oh and on the very faint chance, I took the battery off and tested it for a dead cell, in which it was fine. So gave it a full charge, and put it back on the car to give it a good try whilst cranking.

[Duke137]

Check the earth straps mate?

[Ollie_bwoii]

Ah, did that too. Soda blasted the engine earth.

[BenHar]

Have you lokked through this?: http://www.e30zone.net/e30zonewiki/inde ... oubleshoot

Ben

[daimlerman]

CPS?

[Grrrmachine]

Won't be CPS if he's got fuel and spark. Test bulb on coil would be my guess, and if it's dim then I'd reckon something's loose on the green wire, if it's not the earth straps somewhere.

[Brianmoooore]

A CPS that is failing can still produce 'noise' that can trigger random mistimed sparks, and possibly trigger the fuel pump occasionally, enough to keep some pressure in the line.

[gooner1]

Ollie, have a known good CPS here somewhere.
Give me a shout if needed and I'll try and find it.