99% of the time i find its the fuel pump drawing in air from the oil filter bowl . when turned on the fanmotor should start up and that turns the fuel pump, check the fuel pump is turning, there is a plastic drive on the fuel pump shaft check it is ok. After 15-20 seconds the fuel solenoid energizes and sends fuel to the chamber and the burner fires up . the control box has a small photocell pushed onto the bottom, check it is still on. check you are getting fuel up to the P mark on front of the pump, if not check your fuel solenoid is energizing. if its not it could be broken or you have a fault on the sensing circuit . if you are running a one pipe supply and you have ran the unit out of fuel it will need bleeding. check your electrodes and you are getting a spark, make sure the gap isnt too big or small between the 2 electrodes the transformer for the spark is built into the control box and normaly if faulty needs the control box changing. check all your oil filters normaly a pre filter befor the burner then a filter in the fuel pump then one on the nozzle. hope this helps
farmer
March 2010