I have replaced the following with the problem still happening: replaced the primary control(R8184G 4009), cad cell--the oil unit was service at the beginning of the heating season. Ran like a champ.

Now for the past two weeks with new parts the problem is: Oil burner starts with a flame for about 15 seconds, then flame out for about 12 seconds---then unit flames on until heat temp is reached. Happens exactly the same all the time with new parts. I have a two pipe system, oil lines have flare fittings---everything is tight. I checked the filter still like new from the service. I also primed the oil pump--even though I have a two pipe system. Why is this happening. Now when there is the 12 second no flame and when it comes back on it is a normal ignition --no roar or big explosion just a normal ignition. I have a Beckett AFG unit, Weil-McLain Gold, Honeywell Primary Control/cad cell, High Limit, Suntec two stage oil pump (3450 RPMs), and an Emerson motor that matches.