Have Ultra SX 80 , furnace with fire for 10 sec, then will shut down , will fire again in about 1 min, blower motor is on from start ,doesn't seem to wait to heat up fire box.

First try cleaning the flame sensor.

Sounds like your flame sensor need cleaned it is a little rod opposite of your ignitor. Just rub it with sand paper or steel wool

If that is not it your limit switch may be going bad, how is your air filter is it clean??