[Newell Attack]

Suburban has a thermocouple that keeps the pilot lit after the timer tries to shut the gas valve off. To do that it is positioned in the pilot light flame and if it is warm enough it holds the gas valve open.

If you are getting heat for a brief period of time the thermocouple is probably not getting hot enough. It may be bad but probably just needs to be repositioned to get more heat from the pilot light.