this is probably just a simple fix but im curious if its happened to others if maybe its a mustang thing. my 06 gt is just hitting 50k miles and the gas gauge only reads half a tank while the tank is completely topped off. any suggestions?

 

May be a bad sending unit

 

Bad sending unit or bad gauge.

 

Could be the float on the fuel level sensor. I've seen the brass floats on other Ford vehicles leak and get gas inside them causing the problem you are having. Only way to find out is to get it out of the tank. Not too sure on this one, but in the past you could replace the float alone. Looks like its on the passenger side under the seat and below the large round boot with wires going through it.

I suggest www.alldatadiy.com procedures. I'm not an advertiser for them or anything but I have 3 paid vehicles on there and go there for most of my schematics and breakdowns when doing repairs.