Hi, Meanstreak here with a kinda dumb question, my trucks fuel gauge has been acting up lately, I fill up my truck and it says full, then fifteen minutes later it will go down to E and stay there until I fill it up again. Any ideas on what could be wrong? I thought it could be the sending unit but I don't really have time to test anything right now. Any info is helpful :3 thanks!
That sounds like the float is punctured, letting it fill with gas. You'll have to pull the sending unit to investigate (on the previous generations, that meant pulling the tank). If you shake the float and hear gas sloshing around, it needs replaced. The float is made of two halves of brass that are soldered together. Over time the solder deteriorates and fuel seeps in.
You'll also want to check the resistance of the sending unit with a multimeter while it's out. The fact that there is ever a point in time when the gauge reads FULL eliminates everything electrical outside of the tank.