dual tanks working, but right side gauge not?

[1LOW4X4]

hey guys, i have dual tanks on my 85 c20. they are both full, and the left side gauge works fine. but when you switch it over to the passenger side the gauge just falls down and never moves, no matter the level of gas in the tank. both tanks actually pump fuel, just the right side gauge sucks.

am i lookin at pulling the tank?

heres left side-works fine


passenger tank, no workie.

[GMC Guy]

check your wires first. trace the sending unit wire for the gauge, all the way up to the connection from the circuit board to the gauge itself.

[dabels23]

Sounds like a bad sending unit(in the tank) or a bad ground to that sending unit.

[baclay9]

I have found this is usually due to a bad ground on the sending unit.
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[1LOW4X4]

Thanks guys. So I'm assuming sendin unit is right there stuck in the tank?
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[Chevyman350]

in my 1987 R30 it ended up being that the retaining clip for the float came off, and the ground was almost rubbed into 2 pieces (some how it got routed between the bed support and the frame.)

[Hulk Will Smash]

My right side tank doesn't show on the gauge either, but rather than fall down it just keeps reading the left side. Definately not worth changing the sender, but once I "x" a few more to-dos off my list, I'm going to start tracing wires and see if it's something easy.