Fuel tank reading

[PraisetheLord]

Got an 85 C10 which had dual tanks but only one worked. The working one needed a new sending unit, so while I was at it, I ended up buying 2 brand new tanks, new sending units, new switching valve. I also have Dakota digital gauges.
I put about 5 gallons of gas into one of the tanks and can’t get the gauges to read other than empty. Checked the ground wires and made sure it was good, all wires are connected. I heard someone say to fill up the tank completely to get a reading with the new float on the sending unit. Any other ideas?

 

[75gmck25]

A 20 gallon tank with 5 gallons in it should show a reading that is low, but is higher than empty.

Since you already checked the sending unit ground, now verify that the sending unit wire at the tank has 12 volts when the dash switch is set to that tank. And then if you flip the dash switch you should get 12 volts at the other tank.

 

[ali_c20]

Welcome ! Have you grounded the gauge directly to the frame to see if it moves? It should go up to full. Use the search function of the forum and search youtube, lots of good info there.

https://www.youtube.com/watch?v=ZTMXjITuO8A&t=186s