i have a 1990 mustang when i turn the key on i dont hear the fuel pump is this most likely the pump or can it be a relay thanks

 

It could be either. You should be able to hear the relay click when you turn the key. If it is the orignial, then I would just replace it with a better in-tank it will only help with later mods.

 

There is a kill switch in the trunk left of the latch. Sometimes they just pop up and cause the pump to shut off. I would check that first if that's not it then check fuses and relays. I can tell you that non of the parts stores (at least here in Virginia beach) don't have it and you'll more than likely have to go to ford to get it. Oh on that switch you may have to pull the panel to see it. I would add a picture to this post but don't know how to do it. Once I do I will. Good Luck...