1990 Ford F-150 Leaking gas from front tank cap

it made me to fill hose leaking. or were the fill line hooks to the tank they do make a replacement for the fill line

you have 2 options
1--- put the fuel return line into the tank you are using
2--- install a balance line between tank 1 and tank 2 so that the fuel back to tank1 is allowed to balance back into tank 2

properly set up the tanks should be connected so that the fuel gauge reads the total fuel in the tanks and there is a need for only one fuel pump

Local library.

Hello
Having worked for Ford for 25 years and having seen this very same problem (fuel flows between tank and overflows) many times there is only one cause of the fuel flooding the other tank, the fuel switching valve on the frame rail under the truck is detective, this valve contains special silicone rubber poppet valves that open when the front or wear tank fuel pump is selected, it then seals when the tanks electric pump is shut off at the selector switch, your poppet valves are leaking, all to a common problem. Back in 2000 when I retired this switching valve was no longer sold by Ford parts, it is obsolete. I suggest you check with Ford to see if it is available from some other source or call a local parts store like NAPA or Carquest and inquire is anyone in the aftermarket has them. The last choice is a used one, but of course it could have the same problem as yours as age and deterioration of the rubber valves is what makes them leak.

You definately need to get the truck serviced soon. To just guess at it, the balance pump isnt shutting down. The guage may not connected or moving freely.

You probably have a defective fuel-tank selector valve. Its located on the left frame rail, halfway down. While the vehicle is running, tank"A" is pumping fuel to the engine, while tank "B" is getting the unneeded fuel that is returning from the engine. Thats why it is overflowing.

Sounds as if the seal on that gas cap is old and worn out. Replace the gas cap.

After sitting 2 years, there must have been some fuel in tank that has probably gone real bad (like shellac) and contaminated the fuel system, plugged up filter etc. Usually rust will form in tank, mixed with stale fuel, it will turn just like mud.

there should be two straps holding the tank in place,,,,if you remove them the tank should drop down to where you can disconnect the feeder hose and go from there