I have this product in my car, and it seems to work really well even with a fuel cell.
http://centroidproducts.com/tableofc.htm
The cool thing about this sender is that you can precisely adjust the full and empty level with a tiny screwdriver and they make a sender for either horizontal or vertical mount. Works on pressure not floats which creates the resistance signal to your gauge. They're pretty helpful if you send an email with your particular gauge resistance levels for empty/full.