I am having trouble figuring out why my fj wont start.

What is your question?

I turn the key over and it starts up for all of two seconds and then immediately dies, like its not getting fuel. I have replaced the fuel pump twice, thinking it may have just been a bad pump the first time. After changing the pump the second time, it sounds as if something is shutting the fuel pump off. I have also tried replacing the mass airflow sensor, only resulting in the same issues.