Burner Grey Smoke

Haven’t run this hot water rig for about a month, and it has started putting out a lot of grey smoke. I adjusted the air intake, and that seemed to help a lot. Question is, what could cause the change?

Did the position of the air intake change from vibration when traveling down the road?

I highly doubt. I had to loosen the screws to adjust, and even then it was quite stiff.

Okay, good. A few things could be happening but some are simpler to check so let’s start there.

Is the fuel filter clean? Make sure it isn’t leaking around the bowl. Erratic fuel pressure can do weird things to the fuel/air mixture.

Check your ignitor contact spacing. Needs to be set at factory specs to ensure a consistent ignition and burn. Plenty of videos online on how to do this. Try to find one for your specific model of ignitor or call the manufacturer.

Check to make sure diesel is not soaking the insulation inside of the coil housing. Usually this is due to a dirty fuel nozzle. Instead of spraying in a uniform pattern, a dirty nozzle can spray in a funky pattern and some of that fuel can wick up into the insulation. Can be hard to see but sometimes the smell test is easier. With the burner off, remove any rain shield and shine a bright light in there and see if the insulation looks damp or you may even see fuel pooled up. Again, might not be able to see anything depending on whether you have a vertical or horizontal burner. Take a good whiff and if you smell a strong diesel odor that is likely your problem. As stuff gets hot it starts to ignite that insulation. No bueno at all. If that’s the case, usually you’ll still see some smoke after the burner is shut down. Remove and clean the fuel nozzle. Sometimes you can run some Red Devil additive to help clean that nozzle up.

Beyond that, pretty tough to diagnose things without being there in person but someone more experienced may be able to help.

It’s horizontal. I’ll pull the coil cover off tomorrow and check the insulation. It does smoke a bit after turning off.


No worries man. When you’re not burning the fuel efficiently you’re producing soot and it then causes more problems from gumming stuff up so definitely don’t run it when it’s not running efficiently. Make sure your battery or batteries are in good shape, too. I’m assuming this is a 12v burner and they like to have a steady power source. Check connections, etc.

Also, the #1 thing with ANY diesel burner is you need to have good, clean fuel that is free of contaminants like bacteria/algae, water, etc. If you have aluminum fuel tanks be sure to keep them topped off due to condensation forming on the walls of the tank when they are only partially filled. Maybe take a fuel sample and put it in a glass jar and ensure that you don’t have some bad fuel.

Once you’ve figured out what the underlying issue is, you’ll probably need to adjust that Air Fuel mixture again as well to dial it in. It should be a nice, clean burn with very, very little smoke at all.

Hmmm - just put in some diesel that may have been sitting for at least a month or two. Trick question: is it safe to add bio kleen to diesel after Red Devil has been added?

Now that I do not know. I’m inclined to say that it is probably fine but I really don’t know. Usually, sitting is no problem for diesel fuel. It’s all how it’s stored. If it was in a good airtight container then it’s probably just fine. If there was any sort bio growth in there you’d probably see it plugging up your fuel filter almost immediately.

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I wouldn’t be too worried about it, Run it a while and see if it stops, It can be something as simple as some debris in there like leaves ect… Sometimes weird things end up in those burners you would be surprised.

Be sure you know what you are doing before messing with the Air/Fuel ratio, if you don’t know how to dial it in you can have bigger problems down the road.

My burner started smoking white a little last week actually, but it was after the rain… It must have had some moisture in there, after a few minutes of use it was gone.

Burner repair truly is one of my weak spots, so I’ll keep that in mind. It’s just frustrating, because I’ve had Landa clean it out probably 3 times in the last 5 years, and it really only runs a few times a month.

Post a video and we can better assist you. I’m no expert but I have never paid to have any of my burners fixed or serviced

Will do, thanks.

What’s the secret to uploading a video?

If I choke the air flow, it gets a lot better (pretty much normal) - but I know that’s not the answer, so I put it back to where it was. If air flow is wide open, the burner doesn’t light at all.
There’s a pretty good flow of diesel coming back through the return line into the diesel tank, so I don’t think fuel is restricted. Filter had some rust in it, so I got a new one and put some water treatment in diesel.

Post your video to YouTube then post that link here.

Air intake seems choked a bit much - fires up fine, but then I get some grey smoke when I let off of the gun.