Weak or Yellow Geyser Pilot Flame: What It Means

Weak, yellow or flickering pilot flame: what it means and how to fix it

A healthy geyser pilot burns mostly blue, steady, and wraps around the tip of the thermocouple. A small, yellow, lazy or flickering pilot usually means a dirty pilot jet, poor air supply or low gas pressure, and it is the most common reason a pilot keeps going out once gas is available.

Reading the flame

What you see	Likely cause	What to do
Blue, steady, touching the thermocouple	Healthy pilot	Nothing
Small and weak, barely touching the thermocouple	Partly blocked jet or low pressure	Clean the jet; check pressure
Yellow or orange, sooty	Dirt in the jet or poor air	Clean the jet and air openings
Lifting off the jet, noisy	Draught or too much pressure	Check the flue cap and cover
Bending away from the thermocouple	Bent pilot bracket or draught	Reposition; shield from wind

Why a weak pilot goes out

The thermocouple only holds the gas valve open while it is hot. A small or misplaced flame barely heats it, so any pressure dip or gust is enough to let the valve close. The same geyser with a clean, full pilot may sail through conditions that kill a weak one.

Fixing it

Have the pilot jet and pilot tube cleaned; dust, rust and spider webs are common.
Clear the air openings around the burner and under the geyser.
Check the thermocouple tip sits in the upper part of the flame.
Replace the thermocouple if it is corroded or several years old.
Yellow, sooty flames at the main burner too need a technician: incomplete burning produces carbon monoxide.

Frequently asked questions

Is a yellow pilot flame dangerous?

A yellow, sooty flame means incomplete burning, which can produce carbon monoxide. Have the geyser cleaned and make sure the flue vents outside.

Can I clean the pilot jet myself?

It is a delicate part. If you are not comfortable working on gas fittings, ask a technician; it is a quick, inexpensive job.