[clay68c10]

The fuel sender is a 0-90 ohms type. If you can find a resistance substitution box that would make things easier. Just put it in series between the 12v source and the gage and dial up wheatever ohm setting you want.
The full voltage/no voltage trick also works just so you know if the needle will make a full sweep. The only problem with that test is that you have no idea if the midrange of the gauge is accurate or if it has any dead spots.

Here's a link to the resistance box, also called a decade box.
http://mcm.newark.com/NewarkWebComme...KU=72-7270&N=0
I use one like this at work fairly often. They can come in handy if you have to troubleshoot sensors a lot. I work on Benzes, and they have an a$$load of sensors that like to break.