Erratic Fuel Gauge

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Feb 4, 2008 | 04:16 PM

Terrafermi_1

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Erratic Fuel Gauge

In the past week, my fuel gauge has been reading empty a lot, with more than half a tank. Periodically, it will read full [with maybe 3/4 tank]. It happens after I've had it running for a while [20-30 minutes]. Is this a corrosion problem somewhere[wiring]? Or is the float rapidly becoming useless?

Ideas or suggestions?

Many thanks

1998 F-150, 4x4, 4.6L, 140k

Last edited by Terrafermi_1; Feb 4, 2008 at 04:26 PM.

Feb 4, 2008 | 05:16 PM

steve(ill)

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dont know about the new trucks, but when they did that 20 years ago it was normally the float- sending unit. there is a resistor inside the tank on the sending unit. the float goes up and down and "varies" the resistance with gas level. the gas gauge is basically a voltmeter across the resistor. years back the resistor would rust, corrode, or break and do what you are saying. a bad connection at the tank could also be a problem.--- normally dropping the tank and changing the sending unit was the solution.