The car has spark and fuel pressure is at 58 psi but the car wont start but can run on starting fluid

4.3L , L35(RPO engine)
has 1 fuel pump relay PCM controlled
has 1 fuel pump.oil pressure sensor , too.
not sure at all me what a pulsator might be.Ahh Dampener.
what matters is spark first, it must have spark or the PCM cuts fuel dead on all EFI car. (if the PCM detects spark bad in ANY WAY)
the comes cranking the pump just receiver 12vdc cranking
KEY ON ONLY is only 2sec prime puls best is forget that unless have 2 person to test prime, but cranking matters first.
some new pumps are silent, (like top Bosch) so sounds prove little. today what really matters is PSI pressure cranked,
the PCM brain or the oil pressure switch allow the pump to have power cranked, and running.
that is how to test it, cranked only.

"starting with start fluid,but now it just cranks over ,only."
does this mean starting fluid now fails.?
we check spark at all spark plugs no just 1.
we check oil pressure to, if zero PSI cranked that is bad .
last is fuel pressure if not at spec, it will not start.
spec fuel pressure is 58-64 psi
yes some fuel rails or near by or near tank, have pulsator that is really regulator/dampener.
it prevents old cheap pumps from madly pulsing the rail and causing injectors to mess up. vane pumps do make pulses some worst tan others, (some even by pass it, but there is their call)
Is this a TBI throttle body injection? or MPI.

the SM states this. (it has a 2 second prime for sure)

If the engine does not run, turn the ignition ON, but do not attempt to start the engine. Listen for the fuel pump to run. Within 2 seconds of turning the ignition ON pressure should be 58-64 psi (400-440 kPa) while the pump is running. Once the pump stops, pressure may vary by several pounds, then it should hold steady. If the pressure does not hold steady, wait 10 seconds and repeat this...

Check just after it die to see if you still have good spark at plugs.

Try pulling the dist cap and rotor and make sure they are still in good condition and not corroded

Fuel pressure is a little low. Will it start with a couple shots of carb spray in the throttle body? If it does and continues to run than the fuel pump is not providing enough pressure to to open the mechanical poppet valves on the end of the injectors. minimum fuel pressure is 58 psi. One PSI below spec is enough to make it not start.

Also check to make sure there is spark at each cylinder. just because there is spark at the ignition coil does not mean it is getting the the spark plugs. you may have a bad cap or a rotor that is burned through.

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check the fuel pressure 58-64 PSI

I would start by changing the spark plugs and leads.

Spray some carburetor cleaner into the engine an see if it starts ! I don't think 58 psi fuel pressure is enought ! Has to be above 60 psi .415-455 kPa (60-66 psi).

Fuel pressure for your car should be 50/60 psi you probably need a new fuel pump.

The proper fuel for this s-10 is 58 psi to start the vehicle and it will run on 45 psi but not to good .:)