# Furnace sputtering



## Leo G (May 12, 2005)

Hope to get some advice. My MIL furnace is sputtering. It starts out small and short and eventually the sputters get longer and then it finally times out from lack of flame.

Fresh oil, no water in the system, clean filter and screen. I've replaced the old transformer with a new electronic spark device. Last year we had the system pumped dry of fuel and then new fuel with an anti-water additive.

It's been doing it for quite some time now, a few seasons. I've had "the guy" come by several times and all they ever do is a tune up, filter, screen and nozzle. Even if the guy hears the sputtering he calls it done. Obviously time for a new guy.

So I had a sputtering problem on my system many years back and it ended up being sludge in the line. I used compressed air and blew out a 2' long snake of sludge and that cleared up my problem.

So after trying most normal things I finally blew out the inlet line to her 1000 gal underground tank. I didn't want to do it because of fear of blowing the line and causing real work. But I put pressure into the line and found little if any resistance.

I connected things back up and the furnace hasn't run this good in quite some time (after the initial bleeding), but it is still doing small intermittent sputters. So as the furnace was running I opened the bleeder valve until I got a small steady stream. Every time a sputter occurred I could see a break in the stream.

Mean anything?

I haven't checked the pressure of the pump yet (A2VA-7116 Suntec). It is suppose to be 100psi nominal.

If the pressure is low, could this cause the piston/spring to shut down the flow and cause the sputter? Can it be as simple as raising the PSI on the pump to over come the spring pressure to keep the oil flow constant? A new pump is about $80 and I don't really feel like throwing unnecessary parts at it. But I can't really think of what else it can be if it wasn't a clogged inlet line.

Any words of wisdom for me? Well, besides find another guy to look at it :laughing:


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## hdavis (Feb 14, 2012)

Break in the stream, as in air bubbles? If you hook up clear plastic tubing to the bleeder, you'll see the bubbles if there are any. Otherwise, you're just having a drop in volume.


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## Leo G (May 12, 2005)

Looks like the stream breaks. Doesn't look like bubbles. And if it is they are really big.

I'm thinking the pressure drops and cuts off the piston which stops the flow.

I found a 0-160PSI 1/8" NPT meter at the shop. I'm going to put it on the pressure test port and see what it says. Hoping it's in the high 80s which would make the pressure low and make it hard for the pump to open it. Crank the pressure up and it should stop the problem.....maybe.

Otherwise I have an air leak in the line somewhere or the pump is on it's way out.


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## beenthere (Mar 5, 2009)

Make sure the pump coupling isn't slipping at times. Pump valve opens at 85PSIG. Is this a 1 or 2 pipe system.


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## Leo G (May 12, 2005)

2 pipe system.


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## Leo G (May 12, 2005)

Went back there with a pressure gauge and hooked it up to the Pressure Gauge Port. Fired up the furnace and for the first few seconds it's nice and steady. After that it's jumping +/- 10PSI. When the unit shuts down I think the pressure is suppose to drop 10-20%. It drops to 10PSI and leaks down to zero rather quick.

The only think I'm unsure about is if the port is the same as the nozzle output. I watched a few youtube videos and I think they connected directly into the nozzle port.











Video of the pressure meter.


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## 91782 (Sep 6, 2012)

If at the port, pressure should drop to zero almost instantly. Keeps fuel from dribbling out and making a smoking dangerous mess.

Only been 50 years or more since I worked on one. I recollect those things would get boogered up with black crusty crud #2 fuel oil just naturally leaves behind.


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## Leo G (May 12, 2005)

Ya, I just watched one of the vids again using the manifold tester and they connect it to the nozzle port and then use a valve to shut down the flow to the nozzle. This way it can maintain pressure within the system to check if you have backflow leakage through the regulator.

Still wondering about the jittery pressure.


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## 91782 (Sep 6, 2012)

Leo G said:


> Ya, I just watched one of the vids again using the manifold tester and they connect it to the nozzle port and then use a valve to shut down the flow to the nozzle. This way it can maintain pressure within the system to check if you have backflow leakage through the regulator.
> 
> Still wondering about the jittery pressure.


Its capable of making pressure. You seem to be well-equipped tool-wise.

Make up a short suction line, feed it from a 1 gal or larger container. That will answer the question if there's a break in the supply line.


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## Leo G (May 12, 2005)

Couple of wrenches and a pressure gauge I stole off one of my spray guns. Well equipped he says :laughing:

Good idea drawing from a vessel other than the in ground tank. :thumbsup:


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## hdavis (Feb 14, 2012)

FWIW, you can clean most of the crud out of the system periodically by putting diesel in when the tank is almost empty, then running that. The next thing to do would be a filter change....


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## Fouthgeneration (Jan 7, 2014)

A worn gear pump would fail to produce pressure required as it warms up... new oil is much thinner then legacy bunker oils of the past and have much less sulfur as lube for low cost pump parts :sad:

Check vent on tank for blockage or air "leaks" on any suction lines

most likely a valve seat or spring has nearly failed reducing output pressure/volume below minimum needed for steady firing, check burner orifice for partial blockage/ bad spray pattern?

100.00$ for a new pump and or regulator is much cheaper than a midnight in December repair bill....


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## hdavis (Feb 14, 2012)

Fouthgeneration said:


> 100.00$ for a new pump and or regulator is much cheaper than a midnight in December repair bill....


Worse comes to worse, you can gravity feed out of a 5 or 10 gallon can.


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## beenthere (Mar 5, 2009)

hdavis said:


> FWIW, you can clean most of the crud out of the system periodically by putting diesel in when the tank is almost empty, then running that. The next thing to do would be a filter change....


Diesel and #2 heating oil are the same fuel. Kerosene is thinner and tends to have some cleaning ability.


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## beenthere (Mar 5, 2009)

Looks like you have an air leak in your suction line.


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## Leo G (May 12, 2005)

That's pretty much what I don't want to hear. But I've been coming to that conclusion myself.

What I don't understand is it was really bad before I blew air through the suction line and after I blew air through it, it was 90% better. Now you can't hear the sputtering, you can only see it on the gauge. Whereas before it would time out the furnace it was so bad.


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## 91782 (Sep 6, 2012)

...
http://www.fppf.com/component/catalog/?task=catalog.product&id=21


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## Leo G (May 12, 2005)

Pretty sure we got rid of most of the water problem she had when we pumped the tank dry and put fresh oil with the anti water additive in.

I'm just going to have to get a bucket of fuel oil and see how the furnace reacts coming from a known air free source.


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## 91782 (Sep 6, 2012)

A known source will narrow things down.

You can clean the tank, a line with sludge laying in it will still have it.

One step at a time.:thumbsup:


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## Leo G (May 12, 2005)

What I'm thinking is there is a small air leak somewhere in the middle of the line. There was a 80-90% blockage at the oil tank, the beginning of the line. I blew out the line and felt little to no resistance, but that doesn't mean I didn't blow out 2 or 3" of sludge at the start of the line. Now, without the sludge there the air leak is under a lot less vacuum when the pump is pulling oil. So now I'm getting a lot less air in the line because it's a lot more free flowing.

The problem with the air leak is it'll cost her $10-20 grand to get that tank out of the ground, clean up and put a new tank somewhere in the basement. She's broke.


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## 91782 (Sep 6, 2012)

Leo G said:


> What I'm thinking is there is a small air leak somewhere in the middle of the line. There was a 80-90% blockage at the oil tank, the beginning of the line. I blew out the line and felt little to no resistance, but that doesn't mean I didn't blow out 2 or 3" of sludge at the start of the line. Now, without the sludge there the air leak is under a lot less vacuum when the pump is pulling oil. So now I'm getting a lot less air in the line because it's a lot more free flowing.


Yup. Could be the case.



> The problem with the air leak is it'll cost her $10-20 grand to get that tank out of the ground, clean up and put a new tank somewhere in the basement. She's broke.


Eff the old tank then. Have the smallest, cheapest one you can put in basement. let the next owner worry about abandoned tanks.

Anywho premature to be worrying about all that.


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## hdavis (Feb 14, 2012)

beenthere said:


> Diesel and #2 heating oil are the same fuel.


Except the fractions are different, as are the detergent packs. In other words, they aren't the same thing.


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## 91782 (Sep 6, 2012)

All I know, is here in MI, the road #2 fuel has to be colored, so that when MDOT pulls you over they know if you been cheating using oil bought from the home delivery guys.

It's about $0.26/gal road tax here.

the stuff used at the gravel pits is just plain old #2 fuel oil.


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## hdavis (Feb 14, 2012)

SmallTownGuy said:


> Eff the old tank then. Have the smallest, cheapest one you can put in basement. let the next owner worry about abandoned tanks.


Oil tank laws are a little specialized for me, but I'd be inclined to use a small tank gravity feed like you say, and fill it from the large tank.


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## 91782 (Sep 6, 2012)

Yeah, I know there are laws, then there are practical matters also.


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## hdavis (Feb 14, 2012)

SmallTownGuy said:


> All I know, is here in MI, the road #2 fuel has to be colored, so that when MDOT pulls you over they know if you been cheating using oil bought from the home delivery guys.
> 
> It's about $0.26/gal road tax here.
> 
> the stuff used at the gravel pits is just plain old #2 fuel oil.


You can run kerosene or #2 in diesels. Some diesels will tolerate it long term, and others won't.

What you don't get with diesel is the heavy sludge you'll find in #2 oil tanks. You can practically shovel the stuff out.


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## hdavis (Feb 14, 2012)

SmallTownGuy said:


> Yeah, I know there are laws, then there are practical matters also.




He has enough flow he could fill from the large tank. If it's legit to do it, that keeps from having the old tank "abandoned".


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## Leo G (May 12, 2005)

It's legal if the town doesn't find out about it. :whistling


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## beenthere (Mar 5, 2009)

hdavis said:


> Except the fractions are different, as are the detergent packs. In other words, they aren't the same thing.


No, at least not in PA. It comes out of the same tank at the full depot, its just it has colorant added to it as it is being pumped into the tanker. Unless its ultra low sulfur.


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## beenthere (Mar 5, 2009)

Install a tiger loop, that should take care of that sputtering. https://www.amazon.com/dp/B00AT49UA...t=&hvlocphy=9006773&hvtargid=pla-350428283431

And you won't have to do anything to the tank until it starts to leak. So it saves money for her.


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## 91782 (Sep 6, 2012)

beenthere said:


> Install a tiger loop, that should take care of that sputtering. https://www.amazon.com/dp/B00AT49UA...t=&hvlocphy=9006773&hvtargid=pla-350428283431
> 
> And you won't have to do anything to the tank until it starts to leak. So it saves money for her.


Interesting.:thumbup:


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## Leo G (May 12, 2005)




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