The engine can't burn that much fuel without there being black smoke from the tail pipe. You either have a leak or someone is siphoning your gas.
If no leak can be found, you'll need a scanner that displays live data to view the fuel trim numbers. If they are high positive, the Engine Computer is requesting more fuel. If the numbers are high negative, the computer is trying to reduce fuel without success.
A cylinder misfire, a vacuum leak, and an exhaust leak ahead of the front oxygen sensor can all introduce extra air that will be detected by the oxygen sensor as a lean condition. No matter how much extra fuel the computer commands, there will still be that extra unburned oxygen. O2 sensors only detect unburned oxygen, not unburned fuel. The computer can only adjust fuel metering about plus or minus ten percent beyond factory programmed values.
Thursday, January 5th, 2012 AT 3:44 AM