I have a York Gas Forced Hot Air Heater that ignites and runs for a few minutes then the gas feed shuts down. the small fan motor continues to run, approximately a minute or so later the igniter lights again and gas will flow again for maybe 3 or 4 minutes then the gas flow stops....small fan continues to run, this will repeat its self 3 or 4 times then the system will not re-light. Only the small fan continues to run.