1987 Buick Century fuel injector won't spray

Engine Performance problem
1987 Buick Century 4 cyl Front Wheel Drive Automatic

My '87 buick with a 4 cylinder throttle body injection motor is getting fuel to the throttle body but the injector isn't spraying. The motor will run if I pour a little gas down the throttle body but will not stay running. Also is there supposed to be voltage at the injector when the key is on? There is none on mine. What could cause the injector to not spray.