I turn the switch on the wall on to light my gas fireplace. It turns on for a short while then turns it self off. What is the problem? Thanks!
This might be automatic shut-off because a safety thermocouple is not holding the valve open.
To prevent explosive buildup of fuel in the air, most gas appliances have a thermocouple that provides electricity to hold a magnetic valve open. In a water heater, for example, the pilot light heats the thermocouple, and should it blow out, the gas is shut.
Perhaps there is a thermocouple that needs a minute or so to get warm, and you're not holding the valve open long enough to heat it. Read the instructions for your fireplace.