A short. Most likely between the sender and the fuel gauge.

 

The gauges go down if you unplug that respective connector at the sender. If they were shorted, it wouldnt change if unplugged at the sender Im beginning to think cluster, just making sure nothing stupid can cause it before I spend $250.

 

If there are two wires at the gauge connector you are only disconecting the gauge from the circuit. If it doesn't change when you disconnect the sender, the short is between the gauge and sender. Ring the wire from gauge to sender, disconnected at both ends. If it rings to ground, that is it.

 

Look and see if it happens to have a voltage limiter supplying power to the gauges. I've had them go bad on cars and do that exact same thing.

 

This, bad pulse meter more than likely.

 

Holler at Dale (77NOVA on here). I have a JD455 that I was having a problem with and (like yourself) I came to the Bullet with it. Dale is familiar with these and talked to me about what he thought it was....he was "dead on". Although I took mine to a JD dealer, a simple PM to him may save you that trip.

 

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