Gas Gauge Always Full

[glenmorebuckman]

My wifes '92 Explorer is having problems with it's fuel gauge. It shows full all the time. When you turn the key off it doesn't drop any, but when you first turn the key on it drops slightly then rises to the full mark. If you turn the key off and on , it will drop a little each time until you leave it on then it goes right back up and stays there even with the key off. Is this a gauge problem or the sending unit?

 

[BrooklynBay]

Welcome to this forum! The first thing to check would be the voltage coming off of the sending unit. If you have full voltage all of the time, then it might be a shorted sending unit. Most of the time, it would be the opposite. The sending unit has a variable resistance that varies the voltage signal going to the gauge. The sending unit will eventually have open points, and finally be open (electrically speaking).

 

[unpredictable1]

Man I would give anything to have my explorer replenish its own gas naturally!