I have a 05 v6 mustang and the fuel gauge quit working. For a while it would read E when I would start the car to drive it to work, after the car sat all day the gauge would work on the way home. Now it just sit on E all the time what would cause this
fuel gauge is not working on 2005 Ford Mustang
by highflyer12 in Lexington, KY on October 06, 2010
ANSWER by Superbob , October 06, 2010
Most likely it's the fuel gauge sender in the tank in a module on the right side of the tank, separate from the fuel pump which is on the other side. It's accessable under the rear seat, through an access hole in the floorrpan. the fuel lovel sender will have electrical connections but no fuel lines. If you see fuel lines, that's the pump, not the sender. There's more: the sender wiring goes to a "Smart Junction Box" in the passenger's kick panel area. Reportedly, water can leak into the SJB and cause problems. Check this out. the fuel sender connector is black. Also check for wiring damage under the car from wiring touching the exhaust.
ANSWER by Visitor , October 25, 2010
This is pretty common on the 2005 Mustangs, it's caused by failing stepper motors in the instrument cluster, they control the movement of the gauges. There's a guide on how to fix them here - www.2005-mustang-speedometer-problem.com