Fuel gauge stuck on half full

[Orangejuice]

So my little brother inherited the blue beast because I got a great deal on a gas sipper.

The problem is that you turn the key on and the gauge goes to half a tank and stops. He has maybe 1/4 tank of gas in it.
He ran out of gas last week because he didn't realize that the gauge was not moving lol.

I was wondering if this was a fuel sending unit problem, a gauge problem, or a float problem.

Any help would be greatly appreciated. Thanks

[Orangejuice]

Or half empty

[gadget73]

sounds like the float is somehow mechanically stuck or the sending unit has failed. Normally these read full or empty when something goes flaky though.

[mcninetyone]

You have to check it.
With the key in the "on" position but with the engine not running. You have to get up under the car and ground the sending unit.
If it goes to full on the gauge, it's a bad sending unit.
If it doesn't, then it's probably a bad gauge.
You'll need help, some one to watch the gauge while you do this.

[sly]

If the gauge itself has a loose ground it could possibly do this (though I've never seen one sit dead center). Also, if the anti-slosh module has shorted out in a weird way, it could also do this.