Gas Gauge LSX 77c10

[jrpontiac]

I just completed a 5.3ls swap into my 77 c10. I used GM in tank pump/sending unit from a late 80's GM truck into the original 77 tank. My gas gauge isn't working, it is pegged well past full. The gauge worked prior to the swap.

Is the late 80's sending unit and the 77 gas gauge compatible?

[BR3W CITY]

You'd have to lookup what the Ohm range is on them. If the resistance range on the sending unit is different than the gauge, it will do weird stuff. 0-30ohm, o-90ohm etc

[mongocanfly]

To echo what brew is saying here's a troubleshooting guide that may help....https://www.fillingstation.com/artic...ugetesting.htm

[solidaxel]

What happens to the gauge when you remove the connection to the fuel tank with the key on?

[87chevy.com]

Originally Posted by jrpontiac

I just completed a 5.3ls swap into my 77 c10. I used GM in tank pump/sending unit from a late 80's GM truck into the original 77 tank. My gas gauge isn't working, it is pegged well past full. The gauge worked prior to the swap.

Is the late 80's sending unit and the 77 gas gauge compatible?

Late 80's.... square body? Maybe the gauge was working but the sending unit is bad, or the wire is pinched or fell off altogether.