dealerkiel

just bought my wife's moms 92 firebird. she bought it new in 91, all stock, has 108,xxx. sometimes it will crank and crank and start, sometimes it will crank and crank and crank no start. when it won't start there is no fuel spray from the throttle body but the fuel pump works everytime so its not the fuel pump. the injector resistence is 1.7 where it should be. what voltage should i see at the injectors while cranking and what tells the injectors to spray? the ecm or is there a crank sensor. hope this makes sense im writing fast cause my 2 month old is crying. thanks for any responses.