My furnace is a 1990 model manufactured by Inter-City Products in Lavergne, TN. It's model #NUGE050CG02, with a newer (8 years old?) Honeywell digital thermostat.
It acts normal when I turn it on - inducer fan comes on, gas comes on, igniter lights, burners burn, but this only lasts for two or three minutes, then everything shuts off, including power to the thermostat. I can only get it back on by unplugging the furnace for a few minutes, then after plugging it back in it goes through the same short cycle again then shuts down.
Things I've done so -
1. Checked the flue for obstructions - all clear.
2. Put on a new ground wire for the control board (Robert Shaw brand without indicator lights).
3. Changed all the filters.
4. Put on a new vacuum line from pressure switch to inducer fan.
5. Verified that I'm getting 24 volts to my pressure switch.
6. Cleaned the flame sensor with steel-wool.