If the flame from a gas stove burns blue, increase the supply of air by adjusting the shutter valve on the burner. When the stove is completely cool, expose the burner piping by lifting the top of the unit. Locate the burner's gas valve, and adjust the screw that controls the vent. With the burner on, adjust the shutter until the flame turns blue. Tighten the screw to hold the shutter in the new position.
Gas stoves burn with a blue flame when the air-to-fuel balance is correct. When the air shutter that controls the supply of air becomes clogged, restricted or shifts, the ratio of fuel to air changes. A yellow flame indicates an air deficiency in the burner. The most common reason for air restriction is a blocked or sticky shutter valve. The oils and residue from cooked foods coat the opening or pivot point of the valve over time.
A faulty or oversized burner orifice also causes air restriction in gas stoves. Yellow flames cause irregular heating, soot on the cookware and burner failure. If you cannot locate the adjustment valve or cannot safely lift the top surface of the stove, call a trained gas appliance technician. Discontinue use of the stove until the source of the air restriction is fixed.