2008 Mountaineer - losing gas when car is off?

[NEPA]

Hello guys I've been experiencing an uncommon issue that I've been having with my stock 2008 mountaineer over the past few months. It's probably happened 2-4 times, the last being today.

Car has 80,500 miles

I had 71 miles left according to the LED screen behind my steering wheel. I went to class and when I came back and restarted my vehicle, it had dropped to 41 miles left. I've had this happen before where I'll mysteriously lose 10-50 miles left of gas. What could be causing this issue?

 

[V8SHO]

Does the fuel gauge in the lower left of the cluster also show a lower reading when the digital display changes?

It could be a couple of different things, usually issues with fuel gauges are caused by the sending unit which measures the fuel level inside the tank. Sometimes the sending unit can fail or cause intermittent problems and does not send the correct fuel level which causes a false reading on the cluster.

Otherwise the digital display showing "71 miles left" and dropping down to 41 could just be normal adjustment the computer does using the gas mileage data. The computer calculates the "miles left" based on the recent gas mileage as well as the fuel level in tank. So if you were getting 19 mpg for a stretch and then driving conditions changed and getting maybe 12 mpg before shutting the vehicle off, the change would show on the display when restarting the vehicle.

 

[MotorCityFats13]

did you idle the engine for a period of time before getting out or autostart before getting in.... I once killed off 14 miles just waiting on a train