Why does my beckett oil pump fire up for 10 seconds no problems and then misfire , smoke comes out of bottom of heater, I have replaced the nozzel, the inline filter, replaced the electric igniter, regapped the electrodes, blead the line. I checked the exhaust and it looks like the pumps giving the fuel but the spark isn't there, the exhaust is wet of fuel, please help me , don't want to make that service call. Should I buy a new set of electrodes, my tips on them are worn down is this bad.

Wow you seem to know just enough knowledge to get into a little trouble. LOL And take that comment as a joke.

Do you have the Becket oil burner manual for your burner?
Did you go the manufacturer’s site of the appliance or burner and download it if you do not have the exact manual for that burner?

Not all Beckett burners are created equal and some require different adjustments or ignition transformer voltages to mention just a few differences that need to be accounted for during a tune-up.

Did you do a voltage check on the transformer with a high voltage meter or just do the old screw driver spread test which actually means nothing?
Did you do a voltage check on the transformer with a simulated load to check for transformer breakdown possibilities?
Did you set the electrodes with a tape measure for height above and distance in front of nozzle or did you use a nozzle gap tool especially made for your model burner?
If you replaced the nozzle did you use the one recommended by the furnace manufacturer for degrees of spread, gallon usage, and solid or hollow style or did you just replace what was in there with like same?
Did you check the oil pressure the pump is delivering?
Did you test the cad cell for proper operation?
These are just a few areas that need to be addressed to do a proper tune-up or repair on an oil burner.

I can give you one trick without you answering any of the above questions.

This has driven many people almost nuts over the years and even professional oil burner tune up folks fall for this problem.

Your nozzle is screwed into and brass nozzle holder which is attached to a small pipe that supply the oil under pressure. Many times weather from old age or a service persons strong arm tactics this nozzle holder develops a small almost hair line crack usually starting at the front seat area of the nozzle and progressing back a 1/2 to 1 inch on the nozzle barrel of the nozzle holder. If the nozzle holder is cracked by the abuse as mentioned above it will still look good and the only way you can really tell if it has this crack is to detach the assembly then reinstall with it hanging aiming up in the air through the area where the transformer usually sits. Now the spray will make a mess and that is why I had made a special nozzle holder spray test tool to carry around in my oil tune up tool box years ago.

When you fire up the burner the oil will not ignite since you do not have the transformer connected (make sure of that) and as oil is coming out of the nozzle you will also be able to see if there is a small spray coming out of any cracks in the nozzle holder (look well since the nozzle holder is circular and you have to look all the way around it to be sure). This is a messy way to test for this but unless you have a threaded plug the size of a nozzle thread or have a spare nozzle you can plug up or have a hand held hydraulic tool like I made it is the only way to test this since the newer flame retention burner head will not allow you to really see this area with an inspection mirror through the burner portal.

When the nozzel holder is cracked it will spray oil that will not ignite and cause a very wet flue among other things like smoke. You mentioned this so that is why I took my time to tell you the test procedures for the nozzle holder

Look over what I posted and see if you can supply some more info. Without proper diagnostics all we are doing is a guessing game and guessing games and oil burners just do not work well. As always becareful or you could end up looking like this guy. LOL