On my gas water heater i can get the pilot lit and get the burner to fire but when the burner kicks off the pilot goes out BUT if i manually turn the thermostat down to kick the burner off the pilot will stay lit.....what gives?????
The normal way to check this is with a thermocoupler adapter and a d*** meter.
This equipement would show if the draft from the latent heat of the hot water heater is pulling the pilot flame away from the tip of the thermocoupler when the main burners go off. It would also help show if the problem is within a faulty gas valve.
Does the pilot still go out when you let the tank heat up for a while and then manually turn down the temp controls?