Citroen SM doesnt start

The pump does run with 12V directly. And The lead to the pump from passenger footbay works.
When I do that the car runs on the minimal fuel from the coldstart for one-two seconds.

But the ECU seems not to run the main injectors. I have tested with another borrowed SM ECU with the same result.
(I have not done the work with removing and testing main injectors yet, just checked cold start injector.)

Tjena Johan,

then you need a wiring diagram and follow back from fuel pump to relay and all the way back to ECU. Can you measure on connected ECU, whether it applies ground to pin 19 for 2 seconds after switching on ignition?

I guess that someone has fiddled with the cabling when installing the carburettor button fro fuel pump. Or it might just be classic fault: Is your plus pole on battery firmly tight? There is an additional cable from there to EXU and fuel pump relay that brings +12V to them, If that cable is loose, everything on the car runs, but not ECU and fuel pump. Cold start valve, starter and ignition would run.

Tjena Volker.

I must admit that there was some issues with battery connections, but now battery is changed and new connections very solid.

I have measured pin 16 and 24, there is a solid battery voltage.
I have measured pin 19 with ECU attatched and NO signal when switching on ignition.
I have changed relays.

I have tested with full constant battery to running fuelpump with 2Bar pressure, but nothing other than starting on coldstart valve for a couple revs.

I will have to dive into the cabling..... Any SM owner that have electrical schematics for IE model?

Regards
Johan

Tjena Johan,

so you measured that the exit of pin 19 to +12V never goes to ground, even not for 1-2 seconds after switching ON ignition.

In that case your ECU is broken and needs repair.

Can ECU function intermittent at first and then die completely?
I have tried one other ECU (right number), but have no idea if that one wasnt faulty or not I must admit.

I measured it through wire insulation near ECU to ground and didnt get anything when I switched on ignition.