Make sure the propane tank is full, properly connected to the fire pit gas supply hose, and that the propane tank valve is turned on.
Push in the spark igniter switch to check that is making a clicking noise. If you do not hear a clicking sound, check to ensure the battery is properly installed. If the battery is properly installed, then replace the battery. If there is still no clicking sound, check to make sure the electrode wire is connected. If the problem still persists, the igniter may need to be cleaned or replaced.
Air may need to be purged from the gas supply hose. You can check if the air has been purged if you smell a faint odor of gas and hear hissing near the burner box. If you do not smell any gas, push in the gas valve knob until the air is fully purged from the gas supply hose.
Check for obstructions around the igniter cage and burner ring. Inspect burner tube holes for spider webs. You can clean the burner holes and pilot cage with a heavy duty pipe cleaner and compressed air to clear away debris.
In cold weather, the gas valve knob may need to be kept pushed in up to a minute after the pilot light is lit to warm up the flame sensor (thermocouple).