I'm at my wits end I have an 86 F150 5.0 EFI that has dual fuel tanks, I've replaced both tanks, both fuel sending units (the rear twice), high pressure fuel pump on the rail, switching valve,fuel filter the problem is whenever I use the rear tank the fuel filter hums loudly and if it idles long enough usually less than 5 minutes it goes dead but only on the rear tank, it functions properly on the front tank with no hum .. What am I missing?.. Thanks for any ideas or possible solutions.

 

You have a failing rear in tank pump or your crossover valve is not working
Even if new, those parts can be no good, especially the fuel pump