Tractor Repair: 1086 fuel sending unit, fuel gauge, main tank

Question
Our 1086 IH fuel gauge stopped working. The tank has two sending units. How do I check if the gauge is bad, broken wire, or if the sending units are bad. Fuses seem good. we removed the hot wire from the unit and grounded it and the gauge goes to full.

Answer
Hello,

  By removing the wire and grounding it, you've already verified that the wiring and the gauge are good because the gauge went to full.  The sending unit on the auxiliary tank makes the gauge go from empty to about 1/4, and the sending unit on the main tank makes the gauge go the rest of the way.  To find out which sending unit is bad, check the resistance through them with an ohm meter.  I don't know the exact readings that you should get if they're good, but the bad one will probably not have any continuity at all and you won't get a reading with the ohm meter.