Bryant 3 wire pilot have spark then flame then no spark then pilot out and then repeat again and again cleand pilot why won't pilot stay lite

Thermocouple,, does it have one?

No bimetal

I would guess that your ignition contol module is fualty. If it were a flame sense issue, the sparker would keep sparking. Can you give me the number of the ignition contoll? Sounds like the sparker is lighting the pilot, the flame is being sensed, but when the main valve is trying to open the module is not allowing it, but instead it is starting the process over and over again? If you could post a clear pic of the ignition control, I will see what I can come up with.

Thanks for your help but the problem was the hold valve, when pilot was lite I banged on the gas line and to my surprise pilot stayed lite . Cycled the furance mutiple times and all is OK. Furnce ran all day and night. If this problem happens again may have to replace valve. Again thanks for the help.

Glad its working. Thanks for the update.