In my Fuel Safe fuel cell, I use their SU012 Electronic sender. No floats to get hung up on foam.
It is composed of two concentric metal tubes; it has an potted, sealed electronics box on top about the size of a hockey puck, that bolts on top of the fuel cell plate. The concentric metal tubes can be cut to length desired to match the depth of your cell. No moving parts; the theory of operation is that the gasoline between the two tubes changes the capacitance between the two tubes. Easy to set up; cut the length to match the depth of your cell and install. There are two trim potentiometers on top. One is marked zero and the other is marked full. With no gas in the fuel cell, adjust the zero pot until your gas gauge reades Empty. Next, fill your fuel cell full of gas. Now adjust the full pot until your fuel gauge reads full.
http://www.fuelsafe.com/pdf/Oval%20Track.pdf
scroll down to page 16 of Misc. Racing Accessories
My FuelSafe cell and sender have been in since 1996, and both have been 100% reliable.