Contaminated fuel?
one of the things he looks for is smoke coming out of the exhaust pipe.
He said:
If it's white smoke I won't buy it because that means a blown head gasket (water in the exhaust).
If it's blue smoke I won't buy it because that means the motor is burning up inside.
If it's black smoke I WILL buy it because that means it just needs a tune up so I'll give it to my mechanics to fix up.
I had a similar problem last month but I have a boiler. Smoke was coming out and it smelled like fuel. That’s what alerted me to there being a problem. I turned off the boiler and called the plumber. He changed the blower. He said that “something” was misaligned and it wasn’t shooting the fuel straight but at an angle and that caused fuel to accumulate in the blower and boiler. There was also a bit of fuel which had leaked on the floor right under the blower. Whatever fuel was in the boiler had to be burnt off before the flame was clean.
He did have to clean the boiler because there was a lot of soot. The boiler had been cleaned in Nov.
You sound like a good technical guy. If you judge that this condition is not causing a hazard (like fuel puddling or creeping out the furnace) wait for an oil burner guy to check it out. Diagnosing one of these is usually not that bad, but getting one tuned properly is not trivial, even for a technical person.
I have tuned many, many oil burners and it’s not easy.
If you think that there is a hazard, I’d call a 24 hour oil burner guy and pay him to get it firing properly.
I understand that you are moving soon, so you may want to have the oil burner guy do an inspection while he is there, so you don’t need to call again.
If it has an electric coil operated cartrage type shut off near or on the pump, pull the cartrage out and look at the O rings for damage. Sounds like it dribbles like when you think your done peeing and you reel it on in and your glad your’re wearing your shorts.
Bad O rings is like the valve not being shut off all the way. Valve seat bad or spool rod stuck...same thing.
Some nozzle atomizor tips also have check valve to shut off the drip.
My experiencd is on construction heaters ...big and small.
I’m an all around mechanic, very dangerous to be one.
I concur, get a pro. I had a premature shutoff and the internal reset button didn’t help (that sounds like what yours is doing) and my furnace guy pulled apart the igniter assembly, swapped out a plastic part (he happened to have the right size in his truck), and it fired right up, no recurrence 18 months later. $100.