So are you saying the elec. eye does come into play even during initial startup? Cause it doesn't fire even for it to "not" see a flame. And it does shut down like it should. I guess they can't be too expensive I'll track one down and give it a shot. It's really the only thing I haven't replaced, beside the pump but that it working.
Ok, lets get back to the basics. I've seen everything mentioned except replacing your nozzle and fuel filter. If you have spark, air, and fuel, you should have fire. Many many times, I find a dirty nozzle, which I replace just about every time I touch a fuel oil furnace. dirt can and will get into the orifice, and can cause the spray to spray off angle and not ignite or can be clogged completely which is not hard to do. Nozzle should be replaced every year. Now, it's hard to see if it's dirty, I never clean them unless I want to return some night late. Lets say, your nozzle is stamped .75, on the 5/8 hex end, and then stamped 80A. That is 3/4 gal an hour with a 80 degree angle hollow spray an 80 B is a solid spray If it is 70 B, then 70 degree angle. Sometimes it's on a tag in the furnace on what it takes. If you have a fuel filter, replace it. You mentioned spark. Your checking it right, but how much spark? When you lay your transformer back, in light, take your screwdriver and cover the cad cell until it takes off. Take your screwdriver like you did, and lay it on one spring, slide it over to the other spring, and slowly pull it back. You should get an arc about an inch before it breaks off. If it's a small arc, then your transformer is weak. When setting your electrodes, on an 80 degree nozzle, I like 7/16" from the center of the nozzle to the electrodes. I like my electrodes to be about even with end of the nozzle, and 1/8th inch apart. On a 70 degree , I like all the same, except, an 1/8th" out from the face. Cad cells are kinda rare to be bad, but like it was said, you cant really check unless it's running, I ohm them out, but I don't believe that's your problem. Now, you mentioned fumes. Fuel oil furnaces need to have the soot cleaned out of them. Many furnaces have clean out caps into the heat exchanger, or some way to get into the heat exchanger. The flu pipe should be removed and get cleaned out. If either is blocked, you can and will get fumes. and when you open the door to the burner, heat will pour out at you, and that means you don't have the proper draft. Bottom line there, if you open the burner inspection door while its running, and heat comes pouring out, your not drafting properly. It needs to be a negative draft. Hope this helps. I heat with fuel oil in my garage, and also repair them daily for 28 yrs. Sorry for my bad, I just now seen where you changed the nozzle.
