My 1991 Nissan Sentra will crank but wont start unless I use starting fluid and then it dies shortly after I replaced the fuel filter and the fuel pump
It sounds from here you are not getting fuel. Turn on the ignition, but don’t crank the engine. Do you hear the fuel pump run for 2 seconds or so? If no, check for power at the fuel pump, and then check for power at the fuel pump relay. Also, have someone else crank the engine while you smack the bottom of the gas tank with your hand. If that works, it’s temporary. Have a new fuel pump installed.
I just replaced the fuel pump and fuel filter
Then, I’m going to be blunt, you messed something up.
Look I’m on here looking for some helpful advice I’m positive that I didn’t mess up anything I do know what I’m doing I’m not a idiot
Either your new fuel pump is bad
You replaced a working fuel pump and that wasn’t the problem.
Is your fuel pump getting power?
Sounds like a good first step.
The fuel pump is getting power
Then I would do a fuel flow volume test. If there is sufficient flow at the fuel rail, then you probably have electrical problems with the injectors circuit.
If you hook up the fuel pump so it gets power constantly, what happens?
Maybe the fuel pump is shutting off when the key springs from Start to Run position - or if the oil pressure circuit, detecting no OP, is shutting off the pump.