Why would this oil pump stop pumping?


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Old 12-10-17, 06:40 AM
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Why would this oil pump stop pumping?

I have been troubleshooting our oil burner for a couple of days now that does not want to light up and shuts down. And after checking everything the only culprit that is probably causing the issue is the oil pump.The oil pump is a Suntec AS47C 1538 6P 0700. These are the things I checked:
  • Cleaned oil nozzle
  • Made sure the electrodes produce a spark
  • Motor spins
  • oil pump solenoid:
    • Confirmed voltage on cable going to solenoid
    • Powered solenoid separately and an audible click is heared when engaged
  • When manually sucking on the inlet line oil comes out
  • When manually sucking on the return line and when the solenoid is off and when the pump is spun by hand, some oil comes out. When not spun, sucking produces no oil, confirming good seal in the gear chamber?
  • Completely opened the pump and was surprised how clean it was, I could not find any degradation, no rust, no dirt, no gunk...just clean metal (see attached). The filter had some dirt but nothing major and also cleaned it up before reinstering it I also very lightly sanded the largest surfaces of the pump chamber.
  • The plastic pump-motor connection shaft piece is fine
Here is the pumps data sheet: http://www.suntec.fr/document/docgen...glais/ASgb.pdf

From the datasheet I do see that the pressure adjustment valve is located before the solenoid bypass valve. So the only conclusion I can come up with is that this pressure regulator valve is clogged. But if this was the case how could I suck out oil from the return line when slowly turning the pump by hand.
 
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Old 12-10-17, 06:53 AM
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I'll assume that you have a good Coupling between the Motor and the Pump ?

Did you clean out the gun tube running from the Pump down to the Nozzle when you replaced it ?

I've never "cleaned" my Nozzles because I just wouldn't know if or when they were clean or how they would spray.
 
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Old 12-10-17, 08:04 AM
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The coupling seems fine, the plastic coupling part engages well and has little wear. I even attached a hand drill to the pump, span it and nothing came out of the return path.

I did not clean out the gun tube but if this was clogged the oil should still use the bypass path and go back through the return line? I cleaned out the nozzle by first disassembling it and letting it soak in acetone and then scrubbing the parts with fine mesh steel wool. I could see light through the hole of the nozzle.

However to be safe I also ordered a new nozzle to keep it on hand.

PS: There is no oil leaking btw, everything is dry. There used to be an air leak near the attachment at the oil filter which sucked air instead of oil but this was resolved a while back and was inspected again now.
 
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Old 12-10-17, 09:27 AM
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Originally Posted by brolifen
". . . I did not clean out the gun tube but if this was clogged the oil should still use the bypass path and go back through the return line? . . ."
Correct . . . . and I'm just theorizing that could be what's happening.

I've cleaned out that tube once with a 15" Pipe Cleaner (longer than a Dill's used for Smoking Tobacco Pipes), and found the sludge in it to be as thick as toothpaste or peanut butter, so that the oil never made it to the Nozzle.

No one had even cleaned mine for over 15 years !
 
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Old 12-10-17, 10:20 AM
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You mentioned having a 2 pipe system so you have an allen screw in the return port.

Did you try removing the screw to make it a 1 pipe system and try bleeding the pump.

You didn't mention if this is a new installation or if it's been working until it wasn't.

By doing this you eliminate the nozzle line and nozzle and everything downstream from the pump. If you are able to bleed the pump but still bot get oil to the nozzle you'll know it's not the pump.

Just a thought.
 
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Old 12-10-17, 10:25 AM
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@Spott, the pump does not have a separate bleeding port but it does have a pressure gauge port, I assume I can just use this port?
 
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Old 12-10-17, 11:20 AM
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Well what do you know the pump started working again. The problem was the 3 gear housing screws, out of precaution I probably did not tighten them enough the last time I opened the pump and they probably rattled lose over the last couple of months. The reason why I did that is I noticed that I could no longer turn the pump when they were tight so I was worried it would seize the motor. However after I just tightened them with reasonable force and reinstalled it. The motor was able to spin it fine and it immediately primed itself and the burner lit. At least the new pump will be here tomorrow as to prevent any downtime next time.
 
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Old 12-10-17, 11:40 AM
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When did you order a new pump ?

I thought all of this had occurred this morning.
 
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Old 12-10-17, 01:28 PM
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I was troubleshooting yesterday evening/night and ordered a new pump this morning but this evening it started pumping again .

Edit: well it shut down again, went and opened up the pressure gauge port until it started spitting out oil. It first spit out some air which makes it seem like there is an air leak sucking in air? Well it's burning again I'll replace the pump tomorrow.
 
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Old 12-11-17, 09:11 AM
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Well I guess you should never underestimate human error. My diagnosis was indeed correct, the pump was sucking in air from somewhere. It was from the very source itself, namely the oil tank. My dad pulled up the tube going into the tank way beyond the acceptable limit, perhaps almost a foot and a half from the bottom of the oil tank, when the tank was filled a while ago. So the oil level probably got to a point where some air was getting in and there you go 3 days of wasted troubleshooting and an unneeded new oil pump. I thought I would share the ordeal for any other people with dads that think they can fix stuff..
 
 

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