Hey yall i'm new here and i just bought a 91 f150 every time i switch to the rear tank the truck starts to die. i'm planning on pulling the line going out of the fuel filter to see if it's clogged up nd i was just wondering if there any other things i should check too before taking it to a mechanic to look at the fuel pump and oh in this year model is the pump an internal one or external pump?

 

Both tanks have separate fuel pumps. Before condemning the pump make sure it doesn't run and if it does make sure the valve on the floor is switched to the other tank provided your truck has that feature. Also it would be a good idea to confirm voltage is getting to the pump in question. Sometimes the switch can also have a problem.