Beckett oil burner troubleshooting, intermittent ignition

Our 20 year old furnace needed to be reset a couple times at the start of the heating season - had us a little worried - but when we filled the oil tank it worked fine again .. We wondered if the oil level float guage was a little off .. John T.

Today finished up with changeout of the oil filter and checking the CAD. The CAD appeared fine, not cloudy, and the circuit board easily seen. Primed the system before starting. Oil seemed clean and running. Start up and within a minute, a smaller boom and then a slightly larger one. I immediately shut it down once again.

Next steps?

Dozens of youtube videos out there - perhaps one of them will provide some help - these are just a few examples :

Thanks. I don't think its the CAD. I decided to start it up again a little while ago while this time observing the flame. The flame seems to ignite as it should but then about 30 sec in, I start getting the booms. Not sure if flame related as I shut the door and immediately turn off. So, there does appear to be ignition or there'd be no steady flame for the first 30 sec

google AI info - use at own risk :-)

A Beckett oil burner that ignites"booms" (rumbling or puffing sound), and then shuts down is experiencing a safety lockout, often caused by delayed ignition or improper combustion. The boom sound indicates a small explosion of accumulated fuel, and the shut-down is a safety feature (often triggered by the cad cell sensor) to prevent further danger .  Common Causes for "Ignite then Boom/Lockout" on Beckett Burners: Delayed Ignition (The "Boom"): This is caused by a slight delay between the oil spray starting and the spark igniting it, allowing oil vapor to build up in the chamber. When it finally lights, it causes a "boom" or puff-back. Ignition System Failure: Electrodes may be worn, dirty, improperly spaced, or cracked, leading to a weak or delayed spark. Dirty Nozzle/Burner Components: A clogged or worn nozzle can cause a poor spray pattern, leading to improper ignition. Cad Cell Sensor Issue: The flame sensor (cad cell) may be dirty or failing, causing it to misread the flame and shut down the burner (lockout). Contaminated/Air in Oil Line: Air in the pump (needs bleeding) or poor quality oil can cause unsteady combustion. Blocked Flue/Chimney: If exhaust cannot escape, it causes pressure issues. 

Troubleshooting Steps:

1. Reset and Observe: Push the red reset button once to see if it starts. If it booms and shuts down again, it requires repair.
2. Bleed the Pump: Ensure there is no air in the fuel line (using the bleed nipple on the pump).
3. Inspect Electrodes: Clean and check electrode settings.
4. Replace Nozzle: A worn nozzle is a very common cause of ignition problems.
5. Clean Cad Cell: Wipe off the sensor to ensure it detects the flame properly. 
6. Note: If the burner keeps booming, it is highly recommended to call a professional, as repeated "booms" can damage the heat exchanger and pose a safety risk.