90 bronco gas gauge problem

[rick masters]

I have a problem with my gas gauge.With the truck running it sits on empty,when I shut it off the gauge jumps up to 1/4 tank.I pulled the yellow wire loose on the sending unit ,without even grounding it out the gauge climbs all the way past full.Once I ground the yellow wire out the gauge drop all the way to empty.It is like something is wire backwards .From what I have read grounding the wire should of cause the gauge to read full not empty.

 

[Krafty]

thats because you are perfectly correct the wires are backwards. the yellow wire is the connector to the sending unit according to all of the wiring diagrams I have seen and the black one from the guage should go straight to ground. or end up that way. so ultimately either the sending unit is wired backwards saying the tank is empty when it is full, or the gauge is backwards.

if switching the wires around doesn't solve it then you may have a crossed wire somewhere messing up your signal to your gauge.