My York gas furnace shut off before the blower kicks in. The burner lights up fine. But the burner shut off (about 10 seconds after it lights up) before the blower kicks in. The system keeps trying for three more times.

During the daytime the blower kicks in and the everything works fine for the most time. But at night it doesn't work the most time.

The filter is new.

What could the problem be?

10 seconds is long for a flame sensor problem but you might try cleaning it with steel wool or fine sand paper. Make sure you turn power off to unit before cleaning and back on to test the unit when done.