95 Coupe won't start

The car was driving fine till it just revved a bit then died once moving. I checked the tranny fluid level and it was low (this is my wife's car). after adding fluid we tried to start it but it just turned over. I listen to hear if the fuel pump is priming, but it's not. I switch the fuel pump relay w/ the DRL relay from my Blazer(same #s on both relays) still no prime. I then check all the fuses, but they are all good. I use a can of starting fluid and it runs till I stop spraying.
I dismiss it as a faulty fuel pump and change it w/ one I got from the bone yard. Once I got the old pump out, I test it, and the damn thing works :banghead:
I replace it anyway since the one from the bone-yard is outta a newer Cavi.
After all is said and done still no start. will run on a can of starting fluid but not on its own.
I hard wire the fuel pump and it still wont keep running after I stop spraying the staring fluid. I do hear fuel going thru the fuel rail when it is hard wired though.
I read a few "no start threads" and thought maybe it's the fuel pressure regulator.
But why wont the pump prime on its own?
Maybe it the wiring or a bad ground.
I will replace the regulator, fuel filter (again) and all the grounds I can find.
Please excuse my rambling I just got some bad news about a family member on top of this.

Make sure the strainer and sending unit is not the fault or a bad ground.

Also, make sure the newer pump has the same pressure as the 1995.

Check your oil level. Also check the oil sending unit. If this engine looses oil pressure the module will not fire the injectors. Good Luck.

Is the oil pressure sending unit on the front of the oil pan? I found voltage there at the wire's w/ it unplugged. And I got for continuity at the sensor. but still no fuel pump priming.

The oil sending unit is on the back of the block, under the intake manifold. I believe what you found is the Oil Level Sensor.

ok thanks , guess, the wife will be driving the Blazer for a minute. It's been raining all week, And the car is parked out front in the street. :(

OK. How do I check the oil sending unit? my guess is to do it once it's removed from the car. or to get a plug/wire for it from the j/y and test for continuity(sp) before,while , and after cranking the engine over.