Cadillac Repair: 92 Brougham cranks, wont start, fuel pressure regulator, fuel pump relay

Question
5.0L V8 TBI

Started checking from fuel tank forward. Pump runs for 2 sec when ignition is placed in starting position. Turn key off and fuel can be heard flowing back into the tank.

Replaced fuel filter under passenger side of car in front of rear wheel well. Filter and lines did contain gas.

Checked all related fuses and replaced fuel pump relay.

With key on, pressing the gas pedal doesn't cause fuel to spray into the TBI carb.

Cranks fine and will start momentarily if fuel is dumped manually into the carb.

Will continue to run as long as you add fuel. Stop and the engine quits.

Could this be a fuel pressure regulator problem or a very weak fuel pump? Something else?

Don't have a gauge, so can't check the fuel pressure. The system does pressurize.

Answer
Sounds like a fuel pump to me. But you should really put an external fuel pump pressure tester on the fuel line to actually see what the pressure is at, Because although rare, It COULD BE a fuel pump regulator which is why you need to check the pressure FIRST.