Do you have dual tanks and I assume if you do then both tanks make no difference?
If so, I attached the wiring diagrams. We need to test voltage coming from the selector switch. You have a number of inline connectors that could cause an intermittent issue. However, the always being on full indicates a short to power. Basically this gauge works off of voltage. The more fuel the higher the voltage which raises the gauge.
Let me know if you have questions. Thanks
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Monday, May 18th, 2020 AT 5:59 PM