AFII 85 Beckett Burner cutting out?

Old 01-02-12, 07:30 PM
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AFII 85 Beckett Burner cutting out?

It's a forced-air system, and has run well over the years. I've recently replaced the filter and the nozzle. The burner has a two-line (return) system. It's one of a pair of furnaces in the house, and the other one works fine.

The symptom is that is sputters/bucks/pops. What I mean is, the flame goes out for anywhere from .5 to 1.5 seconds, and will only ever actually fire for 5 to 8 seconds, sometimes less... Almost half-on/half-off.

At one point this was bad enough that it tripped the reset button, which gave me the clue to change the filter and nozzle... Which apparently helped, but did not fix the situation.

I've re-replaced the filter, and paid very close attention to sealing, reasoning that it must be air in the lines. I don't know how to effectively test for the spark cutting out, but I did shut off the oil supply and run it for a few seconds to see if I could see the arc.

I can see it, but only faintly around the flame shield and through the blue glass. I can't say if when the burner shuts off (flame goes out) when running, if it's still firing or not...

So, the possibilities I see:

1) Air in the line
-- tightened the filter strongly, after greasing the rubber gasket(s) well.
-- none of the fittings have been removed, and as far as I know, there's be no trauma outdoors (underground tank)
-- With a return on it, it seems like it should take BIG bubbles to affect it. There are no visible leaks on the filter or lines

2) Spark is going out, for some reason
-- the electrodes look OK to me. They're set about 1/4" apart, about 1/4" above the nozzle and just a hair forward of the plane of the nozzle. They look to me like the diagrams I've seen online
-- I tried a wider (80 vs 70) nozzle. No change.
-- I read somewhere that "rapping" the primary control, if it was flaky, might reveal it to be the weak point. Not so far
-- The transformer(s) don't seem unusually hot or anything odd about them

Ideas for the next step?

Thanks in advance!
Old 01-03-12, 05:32 AM
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I am not that familiar with your AFII 85 Beckett mentioned that you changed the filter and nozzle....that's good. However, the oil pump probably has a strainer. Look for a cap with about 8 bolts on the oil pump...the strainer is inside. If you can not locate a strainer locally, you can get one from the following link online:

Good luck my friend.
Old 01-03-12, 07:20 PM
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The Beckett AFII would have a pump screen but there would only be 4 bolts with probably 5/16" hex heads. The fuel pump is likely a Suntec A2VA-7116 & uses the strainer as shown here: Patriot Supply - SSC-109

The pump coupling could also be slipping.

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