I figured out why my truck has trouble starting every so often...Its my fuel pumps...My truck was doing the same thing before I installed the bigger pumps.When you turn the key on you can here the buzzing sound of the pumps....Why every so often when you turn the key on,you dont here the pumps? That is the reason why it wont start but what could be the reason for the pumps not turning on?I went to ford and bought a new fuel pump high/low relay...Still having the same problem and its getting worse.....Any Ideas???

 

I would see if your getting voltage to the pumps first at all times and take it from there.