Car was running great, next day car would not run. What could be the causes?

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Car would start when I sprayed starting fluid but wouldn't stay running. Checked the fuel pump relay and seemed fine and also turned car over with fuel lines disconnected from filter and no spray. The car was running with no problems prior. Could there be any other things to check besides things to do with fuel pump. Also checked fuses and reset button behind left driver panel. Thanks for any advice anyone gives.