There could be a few issues here...when you switch on, the air fan starts to purge the boiler and flue with clean air. After a few seconds, ignition occurs and the oil supply at the pump is switched on. So - we need to establish if the ignition spark is occurring, or whether or not the oil is actually being switched on. If you have a Danfoss pump, the electrical solenoid on the top of it is prone to failure and this would be my first guess. However, a callout by a qualified OFTEC guy could pay dividends.
John (OFTEC), August 2009