2002 Nissan Sentra how do you check for power at fuel pump replaced it and relay and checked fuse please help still want start will start if you put gas in intake until gas evaporates

If you can hear the fuel pump run, when the ignition switch is turned to ON, the fuel pump is likely fine.

Check for codes. Nissans are notorious for the Camshaft Position Sensor and the Crankshaft Position Sensors failing. This has prevented many of them from starting.