I had a fuel guage read under FULL even when I just filled up the tank. The dealer replaced something and it worked fine until 2 years later, it's at it again. Showing between Full and 3/4 after fill-up. I even tried filling at a different pump just in case it was the pump, but that didn't work. Is this a commom problem and is it a simple fix and expensive part if needed? Any help/recommendation is much appreciated!

 

Plenty of information here http://www.whnet.com/4x4/badgas.html on the subject.

 

Is there a site for how to check and replace a fuel guage sending unit? Thanks!

 

Not that I know of. If you'll notice in the link I provided that a special tool is needed to do some of the work. Replacing the sending unit and fuel guage is probably best left to the pros. It is located under the floor under the rear seat and from what I've heard a real pain to repair. Just my 2 cents.