1990 deville, replaced ecm, fuel pump, filters,

Check fuel pressure system, e.i. file pump pressure, fuel pump itself (most are inside fuel tank) fuel rail pressure (if equipped) plugged or restricted fuel filter.

Possibly the fuel filters are clogged, should be 2 both located on the frame rail, if not these could be your fuel pump relay, I would check these before going for the Fuel Pumps, yes there are 2 one in the tank and 1 on the frame rail.

A mechanic would check the injectors for voltage and for a ground signal from the computer.
The injectors get power from the EEC relay near the battery.
The ECM computer gets a signal for the coil and the injectors from the module mounted on the side of the distributor.

Hello, did you check the fuel pump relay also? It is in position H in the fuse box under the panel on the passenger side. Can you hear the fuel pump run when you turn the key on? Fuel filter clean?
Checked fuel pressure at the fuel rail? If the fuel pump is not coming on, need to determine if it has voltage at the connector on the tank. If voltage is present, and ground is good, then the pump is bad. I hope this helps.

Replace the fuel Pump relay in the Power distribution box under the hood. Also, start checking the wiring harness back to the fuel pump for shorts. Most likely this is the relay cutting out every time it is pumped or jiggled but it is possible, however slight, that the problem is a short.

wrong vacuum line hooked to fuel regulator

check pressure relief valve

That is correct for initial prime,then fuel pump works off of crank sensor.Fuel pump is ussually controlled through ECM not Bcm.Have you checked for fuel preasure when you first turn on key,

maybe ur fuel pump needs replacing. if fuel pump goes out no gas to egnition. or your fuel pump relay might have blown chech owners manual or relays.

Then the engine fuse may be blown it will be marked ECM I think, the fuel pump and injector circuits are two seperate systems, the fuel pump most likely has a stuck relay.