Fraser-Johnston gas furnace intermittent misfire problem

[finnegale]

Hi,

The more the furnace is used throughout the day the more this happens: only one burner out of 5, the one in front of the igniter, will ignite and then shut off after a few seconds.  It does this three times and then the furnace blower turns on with no burners running.  It also throws the general lockout code after the third attempt when it turns on with no burners running.  There is also a small amount of gas smell when this occurs.

thanks for your help!

[Admin]

Is this propane or natural gas?  Maybe the burners or orifices are dirty or the gas valve is malfunctioning.

Worse case there may be a crack in the heat exchanger that causes these ignition issues.  At it heats up during the day the crack would become bigger and may start affecting ignition.  What model is it and are there errors codes?