Ok, my original post was over a noisy draft regulator. Since then I have determined the cause of the regulator banging was the burner going out. This only occurs for a fraction of a second, just little pulses. I changed my in-line fuel filter and my burner nozzle. When I remove the inspection cover I can see this occur. My question is where to look at next. Should I suspect a dying fuel pump ? Or could this be the result of contaminates in the fuel tank ? Has anyone seen anything like this occur >? And, yes, there is over 500 gal in the tank. Unit is Thermo-Pride OH-5. approx 11 yrs.

Go over the suction line to the pump very carefully. The tiniest leak could result in the pump drawing air. More so if the line comes out the top of tank.

Water doesn't burn very well. Could your oil be contaminated?

Hmm, that's a tall order as my tank is buried outside. I did check it with water finding paste and it was a negative.

Hummmm! Perhaps rig up a small supply of known good oil near the furnace. It that doesn't stop the problem, then you will know it is not the tank or line. Keeping much fuel near the furnace isn't a good idea, but a little for a test should be OK.

Well, just as a follow up. I performed Labmans recommended test and the burner ran perfectly. This led me to believe I had air getting into the line. However I decided to recheck my inline filter (one month old) and it was plugged! It turns out I had microbacteria(black slime) growing in my fuel tank. A quick treatment of this agent FPPF (http://www.fppf.com/killem.asp) and I am back in business. Thanks for the help in solving this puzzler. Maybe this will help someone else as well.