Oil boiler won't run from main fuel tank

Old 08-31-13, 09:06 PM
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Oil boiler won't run from main fuel tank

Last winter I ran into a problem where my boiler would only run for about 8 seconds, then the flame would quit, the pump would run for another 2-3 seconds and then stop.

After talking with a tech I did the following

Serviced the system, Replaced the pump, replaced the fuel filter, cleaned the grates, replaced the cad cell, replaced the nozzle, checked the coupler, checked the electrode measurements.

$200+ later, same problem. Tech had me stick vacuum and return hose into a fuel can. Bam... problem fixed. So tech said, that isolates your problem to your lines or your tank.

Unburied lines, they seem ok. Lines are 15 years old, copper, I don't see any cracks or leaks anywhere.

Tank... paid a gentleman $700 to come clean my tank. He ran a vacuum + rotating spray head to clean out a bunch of stuff. Returned about 1 1/2 cups of debris, but was otherwise unremarkable. Now, when hooked up to main tank, boiler runs for approx 30 seconds, then flame goes out, pump runs for an additional few seconds and then shuts off. So.. improvement, but still not fixed. I am still living out of a 15 gallon fuel can, and winter is coming fast. What I do know, is that when I am running the vacuum from the main tank but keep the return dumping into the fuel can so I can see the stream is I get bubbles in the fuel after about 15-30 seconds... that is also when the boiler starts to lose flame. So that tells me that I am getting air somewhere, but I don't know where.

I have the suntec B2YA-8916. I see it has an adjustable screw near the inlet, from what I can tell that's for pressure. Is there any other place I can check for vacuum leaks? I have NO fuel leaking anywhere that I have been able to find. And the boiler runs fine with 5 foot of rubber hose for both vacuum and another one for return stuck into a fuel can. But it wont from the copper lines to the main tank. I am desperate for suggestions as I am now down almost $1000 so far. Before I pay another $300 for a tech to come to the house I want to see if there is anything I can do myself.
Old 09-01-13, 12:46 AM
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The problem would be with the supply line. If the return line had a leak you'd be seeing fuel.

I would disconnect the line at tank and apply a vacuum or pressure to it to find leak. If the problem isn't in that line then it's in the fitting at the top of the tank or the tube in the tank that picks up the oil.
Old 09-01-13, 01:45 AM
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Do you have a suction lift on the system? By this I mean is the fuel tank lower than the burner? Do you have a canister-type fuel filter between the tank and the pump? Is so, where is this filter located? What kind of fittings are there on the suction line, flared or compression?

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