i have a tbi 350 truck that i just put together when i go to start it the ecm delays the fuel from the motor for about 20 secs. it wont prime the fuel it wont fire the injectors and turn the fuel pump on till about 20 secs in on cranking it over. even when i crank it for few secs like i normaly would it still wont start untill it cranks over for around 20 secs basicly 3 trys to get it started. i dont know why ecm wont even prime the pump ive replaced the relay ive tryed differant ecm all of them do the same thing. anyone know anything else i could try?