My Tempstar furnace will ignite and then go out when calling for heat. This will repeat itself several times before remaining lit. Any suggestions for repair? I have taken the pilot assembly off and cleaning it. Cleaned the sensor wire connection and all mating surfaces.I do know it is a smart valve with flame sensor so I checked there first.Everything seems OK but when it calls for heat the draft inducer starts. Then pilot will light. Then the burner will light and go right back out.then it will repeat this process several times until it remains lit. After it is lit it will remain lit until then t-stat stops calling for heat?

With a smartvalve I don't remember if there is a separate flame sensor or not. If there is, remove & clean it with fine steel wool or a scotch brite pad.