When I park my car facing downward in my drive way. Front end 1st. If I have less than a 1/4 tank of gas the sensor tells me I am low on fuel and only registers empty. Then when I pull out and drive for a while the gas gauge goes back up to around 1/4 or more. Wasn't able to start car today as a result of this. Is the fuel sensor in the back of the tank? Could this be a reason for this problem? I went and got gas in a can and filled the tank with 5 gallons. When I started the car and drove it to the station to get more gas it registered almost half a tank. What gives?