so im pretty sure my 1991 f150 has cross flow. i filled it up and then i didnt run it for a day and im already down a quarter. and tonight when i walked outside my rear tank pump was just randomly running. the front tank dosent rejestor so i dont no how much is in it. how do you fix cross flow or to make the front tank rejestor.

 

Everything is inside the tank.. the pump, the check valves that are supposed to prevent crossflow, and the fuel level sending unit(float), so you'll have to drop the front tank and replace the complete fuel delivery module(FDM) and fit a new fuel level sender.