2000 chev blazer 4.3 4wd CSEFI won,t start have

2000 chev blazer 4.3 4wd CSEFI won,t start have spark, pump is running,fuel pressure is 55-60 as specified. Tried the crank sensor with no result is it possible that the fuel pressure regulator is not giving the correct fuel to the injectors or might it be the fuel meter body. Something is not letting the injectors spray fuel. It will fire if fuel is sprayed into throttle body,all wiring looks good, ran fine before this occured. What else will prevent the injectors from spraying