When the furnace burner ignites it makes a sound like lighting a gas grillwith a lighter.it does not do it every time the furnace burner ignites

You may have a model of furnace that works just that way. How it works is when you turn on the thermostat to get heat in the house it activates a "sparker" this is what you hear. This ignites the gas at the pilot and after the pilot heats up a strip of metal it moves a switch that turns on the main gas valve and the pilot lights the burners. The clicking should stop about the time or a little after the burners light but it is not going to hurt anything if it does not stop at that time.

Sorry I misunderstood what you were saying you post, but now I think you are saying that it sounds like too much gas is there and when it lights it makes a noise.

The main thing that causes this if your frunace is several years old it the pilot strip needs cleaning. To do this you take the burners out of the furnace and dust them out and scrape any rust that you see in the little line in the burner next to where the pilot is, or if you want to try it hit each burner with a heavy screwdriver, try to know the rust and dirt out of it. Then turn the pilot off and let it cool for thirty minutes or so and then use a hand held vacuum to clean out the burners. No relight the pilot and see if it still makes the noise.

Let me know.