Fuel tank level sensor

I am going through this exact same issue with an AT input for the fuel level. I get a decent reading with the key on but as soon as I start the car it all goes too shit. I’m going to overlay new wire from the sender to the M1 and switch to a AV input with an external 300ohm pull up. Fingers crossed.

Does your fuel system return fuel to the tank? Perhaps the sensor is subjected to the flow of return fuel and get's confused regarding the level.

Mine does return fuel to the tank. But the return line feeds directly into the bottom of the fuel bowl inside the tank. The float is attached to an arm that places it outside the fuel bowl.

Ok just overlayed the 2 wires for the level sender, switched to a AV input with a 220ohm pullup resistor. Same result, I start the car and the voltage goes from .094v to .452v. Im thinking I may need to calibrate the translation with the engine running instead of manually moving the float outside the car to get the high and low values. Just seems odd that the engine running has this effect.

screen shots attached