That Sounds like a very dangerous problem. You Must Get This Checked By a PRO!
Low Gas Pressure could be one cause another is if you use hot air heat the return ducts could be turned off or closed, forcing return air through the flue and the chimney.
Here is a quick test. with the water heater pilot lit open the door the the living quarters Basement door, turn heat on if water heater pilot stays on then you got a blocked
return.
You really should get this checked by a pro. Also please get a good c0 dector
Have you turned the control from Pilot to On? Have you increased the temperature setting?
Gas not turned on to water heater. Gas valve on water heater not set to pilot setting. Faulty gas valve. Igniter for lighting pilot not working.
low back, spillage, or a bad thermocouple.
"Pilot" is only when initially igniting your water heater. Some manufacturers state to leave it on "Pilot" for so many minutes before turning to on but this is only temporary. It should be then turned to "On" and then if you have a low, medium or high setting or degrees adjustment, adjust the temperature setting. Remember that most local plumbing codes and water heater manufacturers recommend a temperature of no more than 120 degrees F.
If the pilot light is on, the heater should come on by itself. If the pilot light is off then it has to be lit. If it will not stay on, the thermocouple is bad.
Gas water heater has an orifice for main burner and for pilot light, if not electronic ignition.
Yes
Thermocouple. Keep pilot knob depressed for 30 seconds after lighting pilot.
The water continues to run into and out of the water heater. There is just no flame to heat it up.
Thermocouple is most likely the problem but it also can be wind and draft which blows out the pilot light and very rare it can be you have a air pocket in your line or sometimes condensation can drip on the pilot. If you have a flame when starting the pilot light as you are pushing down on a non forced air gas water heater and the pilot goes out after you release the pilot handle then 90 out of a 100 times its your Thermocouple. If you have a forced air tank type gas water heater it can be a lot more sophisticated and I recommend you read your manual trouble shoot guide and follow those steps for YOUR specific water heater.
Right below the thermocouple if applicable
No.