Welcome to FSC forums. A lot of knowledgable people on here will help out. I also have an 87 with dual tanks. One thing I have discovered is that the fuel selector valve and fuel tank are 1 year only parts. My passenger tank has a fist sized hole in it, so when I switch the switch, it dies instantly. I need to pull the tank and check the sending unit, I know the pump will be bad, just hoping that the sending unit is OK. Then I can fix the tank, put in a new pump, and then check my fuel selector valve. I have been running 1 tank since I bought the truck, but it gets such lousy fuel economy that i really want that second tank to work.