96 sunfire only starts sometimes

hi all
i hope someone can help with this
my 96 sunfire 2.2 has a mind of its own-sometimes i will turn the key on and i hear the fuel pump come on then turn key and it cranks and fires right up
other times i turn on the key and the pump doesnt come on so if i proceed to start it will crank forever but never starts
i have replaced the relay and the sending unit and it still does it
other than the intermittent starts the car runs fine so if anyone has any advice or ideas they would be much apreciated

thanks

fuel pump is dying. get it replaced

fuel pump is dying. get it replaced

i replaced the sending unit so i assume that the pump inside it is also new
also the last couple of days its been starting fine on the first try