I don't know if it's your ECU man; the fuel pump doesn't use the ECU to start running, it uses the starter signal for that.
Once you cut the starter THEN the ECU takes over control. So if your ECU is the problem it should start then die.
I'm not going to tell you there's no way it could be the ECU, but it's pretty unlikely IMO. More likely is 1 of the 2 relays for the pump.
The pump control relay is easy to jump if you don't want to spend the money on it. If that doesn't fix it pick up a new COR [Circuit Opening Relay] and throw it in.
As far as your ECU, you "need" an RC ECU. A Grp A or CS one will probably work find also, judging by how the US vs JDM ECUs work.
Also FYI; Either a 92/93 JDM or an RC ECU will both work find plugged into a US 92/93 harness, no wiring needed [The RC will throw a CEL because it doesn't have the IC level sensor hooked up, but the engine will run fine].
With that said, I'm guessing a regular JDM or US 92/93 ECU will run the engine fine plugged into an RC harness. I can tell you with certainty it won't have any problems with the RC AFM because I've ran and RC ECU on a regular AFM and a regular ECU with an RC AFM [I wanted to see what would happen with both. Nothing at all, ECU didn't even notice].
I don't know if either would control the IC pump though. But just to check for starting, I'm guessing they would both work.
Something else you can try is jumping TE2 and E1, leaving the jumper in and seeing if you get any codes when it does that. Unlikely, but worth a shot IMO. And it's free.
I hope that all made sense. GL