Engine starts and dies. Pump pressure is around 54 pounds. If starting fluid is sprayed into throttle body car continues to run until it burns all fluid. Therefore spark is present. Something is shutting off the fuel pump within a few seconds. Any thoughts

 

I would get a multi meter out and check the crankshaft position sensor. The initial start up is from the fuel when the rack was pressurized. Once the engine is cranking over the CKPS tells the ECU the engine is turning and the ECU in turns starts the fuel pump and controls ignition and injector.
If the sensor is dead the ECU doesn't know the engine is trying to start. The camshaft position sensor is supposed to defaul and take over but doesn't always do that.