My Vans fuel gauges never worked and I tracked the problem to engine start. During the start the battery voltage dropped to below 7 volts and when this happened (often) the fuel gauges quit working and would not restart until a power down. I proved this by removing the fuel gauzes and replicating the problem on the bench with a viable power supply. My conclusion is that itís a design flaw but a silly workaround would have been to power the gauges through a NC push button switch. When the problem happens after startup, push the button and the gauges would reset and work fine. I choose to buy another brand of fuel gauge instead.
RV7A Flying, N789W