My 2000 Chevy S-10 4cyl 2.2L is burning to much fuel. The fuel gage needle goes up and down when driving. When you start it up the gas gage will go down a notch. I have new wires and spark plugs in a motor that is two years old. It seems like I'm only getting five or six miles to the gallon. What could be wrong?
Probable causes of an engine running rich are as follows:
1.Excessive fuel pressure can be cause by restricted fuel return line
2.Defective Oxygen Sensors.
3.Leaking injectors and fuel pressure regulator.
4.Coolant temperature sensor out of calibration.
5.Restricted air intake system.