I have a 1987 F150 XLT Lariat with dual gas tanks I recently purchased. When switched to the rear tank position the gas gauge appears to show FULL (I know it wasn't I put 17 gallons in it). I smelled a heated plastic smell in the cabin of the truck and investigated. It is the wiring and wiring connector to the fuel switch that is overheating. I switched back to the front tank and it doesn't seem to have this problem. Any Suggestions?

 

Test the current draw (amps) through the switch in each position. If it's pulling much more for the rear tank, trace the wiring fault in the fuel pump circuit. Then replace the switch. If it's pulling more in the front, just replace the switch.

 

Thanks Steve83...I'll check it as soon as I can dig out of this snow.