: The pilot on my gas water heater will not stay on for any lenghth of time. Have replaced thermocouple but did not do any good. Check for a safity shut off that may be wired into the thermocouple circuit this may go to a spill swicth on the flue deverter or a high temperture limit. Or you may have a weak pilot Remove and clean the piolt assembly. or a bad gas valve. Call a profesional, or you gas company. Improper operations of a gas appliance can KILL.