dual fuel tank gauge not working

[bakerboys]

have 85 Chevy K20 4x4
was a diesel now 350 has dual tanks both do work but gauge will not work
my gauge stays om past full all the time
hooked up another gauge panel from junkyard and fuel gauge went straight past full mark

Checked all grounds seem to be hooked up and grounded

I dropped right side tank because it leaks
noticed tank on driver side seems to be wired differently

Any thing I can LOOK for thanks

[wilkin250r]

Typically, your fuel gauge pegged past full is an indication of a broken wire, bad ground, or bad sending unit (because the typical failure in the sending unit is the fine wire of the resistance coil breaking).

You can check by either pulling the wire off the sending unit and connecting a known fixed resistance to ground and seeing if the fuel gauge responds accordingly, or you can attempt to read the resistance of the sending unit directly.

[hatzie]

Short the pink striped sender wire to ground and the gauge will read stone empty as long as the wiring is ok.
Pegging past full is usually an open in the gauge wire or a bad frame-to-sender ground.

[jhngardner367]

You might also want to check the fuel tank selector switch wires,as they go through it,so when you switch tanks,it switches sending units,also.