The ECA , in this case, is supposed to provide the ground for the fuel pump relay for 2-3 seconds when you first turn the key on. After that, the RPM signal from the dist and ign module supply the ground.
It could very well be a problem with the ECA , but we should make sure somebody did not hook up a permanent ground to the relay to defeat the system.
If for instance they provided a constant source of power to the inertia sw that could be one of the reasons the fuel pump runs all the time. This is what we mean by "Altering".
Even then the pressure regulator should control the pressure ,which the reading indicates it is doing.
Something we should confirm, the on time of the fuel injectors, and special equip would be needed to do this because we would be dealing with milliseconds.
That number should be in the area of 2-3 milliseconds. At this point , it could involve the computer and they didn't want to spend the $$$ so just left it.

Another afterthought, we don't know where they took the power from to by-pass the inertia sw and that could also get into the picture if that is what they did.

 

There may be another relay with the same part #, possibly for a/c? It is possible the contacts in the relay have stuck and would be worth looking to see if you can substitute it for test purposes.

 

I think we better take this one at a time. Just about ALL ground wires are BLACK with White tracer.
Both fuel pumps normally get power from the fuel pump relay THAT GETS IT'S POWER FROM THE EEC power relay and closes when the key is on. Power goes through the inertia sw to in tank pump and hi press pump, ONLY the first 2 seconds key is turned on OR ,,,,,when engine is cranking or running. .
1. There is a terminal in the test connector that if grounded, will close, PROVIDE GROUND,the fuel pump relay and cause the fuel pumps to run continuously when the key is turned on ,,,for test purposes! We don't know if they grounded that terminal permanently.

2. We need to determine if they connected power all the time to the inertia sw AND, IF THEY DID, WHERE DID THEY TAP INTO FOR THAT POWER ?
The answers to those questions should clear up some things.

 

I’ve got an update for y’all. We did end up replacing the computer which solved several problems. The fuel pump primes correctly and shuts off when it’s supposed to. It no longer wants to stall in between shifting gears. It does idle smoother, but it’s still not right. It still runs pretty rich at idle, but as soon as I get going, it runs perfectly. I guess the next thing is to check the power going to the sensors I replaced.