Demon-possessed gas gauge

2004 Ford Explorer Sport Trac - Gas gauge indicator arm swings wildly beyond normal arc of travel and lies on one side or the other of the E & F labels in a seemingly random fashion. Some days, the indicator restrains itself to travel within the usual & customary manufacturer’s boundaries. Other days, it falls to one side and listlessly rests there until it flops to another position, independent of the amount of gas in the tank. Ford dealer said that this intermittent activity cannot be corrected until the gauge fails completely and forever. Exorcism comes to mind. Your thoughts?

@syoder Speaking from experience (we also have Sport Tracs in our fleet), the fuel level sender is probably failing.

The accuracy of the gauge and wiring can be tested by using a decade resistance box in place of the sender. Using this, you can simulate 1/4, 1/2, 3/4, full tank, etc. The gauge should literally indicated what you dialed in. If it does, the gauge and wiring are fine.

The accuracy of the sender can be tested with an ohmmeter once it’s removed from the tank.
It’s supposed to have a certain resistance full versus empty.

I’d say your Ford dealer hasn’t been trying very hard to diagnose your problem.

I don’t even work at a Ford dealer and I haven’t had too many problems diagnosing Ford fuel gauge/sender complaints. All I’ve needed so far were halfway decent wiring diagrams and component locators. A few times I didn’t even have those.