Fuel Gauge pegged

[JeepFanactic]

My MJ has been sitting in the garage for a while.  Started it up today and the fuel gauge reads past the full mark. I haven't driven it in a while. Any ideas? Thanks 

[rylee144]

mine did that when the fuse was out. might check that.

[Eagle]

For the '87, I believe the fuel gauge sender has the same resistance range as the other gauge senders, 0 -88 ohms. 0 ohms indicates empty and 88 ohms equals full.

 

A short circuit would result in zero (or nearly zero) ohms and would indicate empty. A broken wire would indicate full. You probably have a broken wire or a bad ground.

 

[JustEmptyEveryPocket]

3 hours ago, Eagle said:

You probably have a broken wire or a bad ground

Or maybe you have an awesome magic truck that makes more fuel for itself the longer you let it sit...... but probably its a broken wire.

[omega_rugal]

broken wire, bad ground

[JeepFanactic]

How do I check for either a broken wire or bad ground?

[Ωhm]

At Fuel Pump Motor, disconnect C139. On the Fuel Gauge side of the harness, ground C139_B. KEY ON. Does Fuel Gauge read Empty? On the Fuel Sender side of harness take continuity test between C139_B and ground. Does ohmmeter read between 0-88 ohms?