Electrical problem
2004 Chevy Tahoe V8 Four Wheel Drive Automatic 120000 miles
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About 6 months ago we started running out of gas when fuel gauge showed 3/4 of a tank. The vehicle would be driven to our driveway, but then would not re-start without us putting in 5 gallons of gas. Now the problem has escalated to out of gas at 1/2 tank showing.
Not sure if we have a bad gauge, sensor in tank. Pleae advise where to ck.

since its erratic like that i would really suspect a bad sending unit, you can take and add a + volt to the singal wire on the harness tank shoudl show full add negative 12 it should show empty.

if that works properly then the sending unit in tank is bad.