Originally Posted by fmc400
Float arm could be stuck (less likely), rheostat in the sending unit is shorted, or a short to ground somewhere between the sending unit and gauge. Pull the sending unit lead and see what happens.
I assume the temperature gauge does not peg toward H?
I do believe you were correct about the float arm being stuck. I went for a drive yesterday hit a couple of bumps and all of a sudden the gauge went down to the half mark, which is about right. I think I'll still take the bed off at some point and look at the sending unit and see if I can clean it up a little bit, and look to see if there's a bunch of junk in the tank too. So for now, problem seems to be solved. Thanks for everyone's help!