OK FELLOW SERV. TECH'S HELP ME OUT HERE!?

My last thought would be the valve. I would bet your losing voltage to the valve somewhere somehow. Only five to six seconds is too quick for the high limit to trip, and the roll-out switches are manually reset so that wouldn't be it either. My best three guesses.

1. Flame sensor needs cleaned

2. Circuit board malfunctioning.

3. pressure switch cutting out

- start with the flame sensor, a small rod that sits in front of the burners, typically located in front of the burner completely opposite the ignitor sits in front of. Get a 1/4 nut driver, pull it out and clean it off with emory cloth, if you don't have this than use a mint dollar bill that is clean.

Well, I don't know why they did or even if they did but I do know that the actor Wallace Beery seemed to have come close to actually saying it in the movie Treasure Island when he played Long John Silver. Maybe we get that pirate thing from watching him during that movie in the late 30's or early 40's or maybe he found some writings of pirates and was making his character a real as he could. When I think of pirates, I used to always think of him. Now I think about Johnny Depp as Jack Sparrow.

In your situation its going to be a sensor the senses the air to gas mixture. (forgot the name of it). Check your sensors on or around the igniter and burners. If you don't find anything wrong there, then it could be your gas valve.

If its a condensing furnace clean the condensate drain and the trap.If its plugged it will trip pressure switch.

Check the pressure switch connected to the inducer motor by rubber tube. It'll have two wire leads coming off it.

Flame sensor needs cleaned.

don't forget the limit switch. faulty limit switch could be, maybe, shutting down the valve/system. GL with it.