Fuel issues

[mbfshs2004]

Seemed to start after adding a can of sea foam with a tunnel at the gas tank fill hose. Timing could be coincidence but started about the same time. Fuel gauge is stuck on full. When turning the truck off the needle drops to empty so the needle isn’t stuck.

When filling with gas the fill hose backs on almost instantly and have to pump very slow to add any gas but then still fills prematurely. Really I don’t seem to be able to add more then about 4 gallons.

I seemed mostly confused but the 2 issues combined. What could cause both these issues.

 

[JamaicaJoe]

How much fuel in tank when you added sea foam?
How far have you driven?
Why did you add sea foam?

 

[mbfshs2004]

Added the sea foam to about half a tank so probably 12 gallons or so as preventative maintenance. At this point that was probably 150 miles ago.

After adding it I drove probably about 25 miles before filling it up and noticed at that point the guage showed half a tank but it was clearly lower then that based on the amount of gas it took.

 

[Trainmaster]

How about the fuel pump/sensor falling apart inside the tank?