I light the water heater with the electric igniter then turn it to on. It will light and hold a flame for a while. After while here a little sizzling noise but I suspect it is from condensation. It will still burn then shut off. I noticed the water is not as hot as usual it is luke warm. Then the water heater won t restart after I run the warm water out. Seems to take out the pilot also. What could this be?