FUEL GAUGE IS MOVING ALL OVER THE PLACE
This is caused by 2 things:
1. Incorrect fuel gauge/sender match
2. Fuel slosh in an un-baffeled tank or open tank or fuel sender in a position that allows additional slosh. Best practice is to have the sender oriented 90 degrees to the fore-aft (should face one side or the other vs. front-to back)
How can I dampen my gauge
NVU gauges are high-speed, high accuracy performance meters. Additional dampening will affect the speed in which the gauge reacts to changes in input.
If desired you may be able to add a capacitor to dampen the fuel gauge electronically. The bigger the better.
HERE IS A LINK to a drawing with part numbers for a capacitor that we have found to work well on 73-10 and 240-33, it has not been tested on other ranges.