Dave,

Sorry I overlooked the details on your top post. I might have saved you the RPM sensor experience, since you wouldn't have got the "OK SPARK" with a bad RPM sensor.

Right now I'm stumped, since you already tried another Fuel relay, which needs only 2 things to energize it:
1) 12V from System relay 87/1 (which did power Injectors, etc, allowing engine to run when you manually closed the Fuel relay).
2) Ground from FI ECU to Fuel relay 86/2 coil terminal.

Now I'm also thinking that your first clue: "I cannot hear the 2 sec. hissing of the fuel pump when turning the key." is more significant than I first thought. Having seen ECUs that fail to do the 2 sec. test but otherwise operate OK, I skipped over it.

I don't know the internal ECU details, but for both that Key On "2 sec. hissing" and normal pump operation, the ECU must put a ground on Fuel relay 86/2.
[I'm assuming here that the Green (dual) fuel relay has the same terminal configuration as the more common White one.]

So maybe you have the (known) LH 2.4 ECU failure to provide that critical Fuel relay ground. On a 240 it would be easy to verify by back-probing a ground jumper to 86/2. It might also be possible on your 940 SE, but I'm not familiar with removing the relay rack for access to the underside.

Hopefully older and wiser heads can chime in here. Post back with the last 3 digits of the ECU Bosch number and label color (pink vs white) and watch the for responses.

--
Bruce Young, '93 940-NA (current), 240s (one V8), 140s, 122s, since '63.