sunfire fuel problem

Hi all Can anyone tell me what causes the throttle body fuel injector to inject fuel while cranking ? This car will start only if I put gas in the throttle body to prime it as no fuel is coming out of the injector while cranking . It will inject and run normal once primed . I've had to connect a jumper from power to the injecter wiring (just touch the wires briefly ) so it can prime then crank to start . Thanks in advance