Yellow flame on Masterbuilt 7-in-1

Discussion in 'Propane Smokers' started by bigjim1979, Mar 16, 2013.

  1. bigjim1979

    bigjim1979 Newbie

    I've had a Masterbuilt 7-in-1 for about six weeks now. I really like it--very versatile and turns out excellent food. From the start, though, the propane burner has produced a very yellow flame. I'd say it's about 30% blue and 70% yellow when high, maybe 40% blue and 60% yellow at the lowest setting. Very sooty. I contacted Masterbuilt (great customer service) and they sent me a new burner/regulator. Same problem. Both units burned yellow from the start so the problem isn't related to soot buildup or any kind of blockage. It burns bluest with the air adjustment set wide open so I can't give it any more air. I've tried different propane. I'm at 2500' elevation, temperatures have been mild. Any ideas? 
  2. dward51

    dward51 Master of the Pit OTBS Member

    Yellow flame is a sure sign of insufficient oxygen and an incomplete burning of the gas.  Your "sooty" comment is a further indication it's a low oxygen problem.   I would disassemble the burner and see if perhaps there is some casting flash, packing material or a small spider web partially blocking the flow.  Odds of getting two bad regulators and low, but it's possible.  Masterbuilt seems to be going trough a spell of quality control issues on there electric models so I guess it's possible.

    I would pull the burner and start inspecting it next though.
  3. daveomak

    daveomak Smoking Guru OTBS Member SMF Premier Member

    Jim, welcome.....  New propane tanks are equipped with idiot valves...   To overcome the guvments auto shut down device, turn off the smoker gas valve, close the tank, open the tank VERY slowly, open the valve on the smoker and light it.....  I the flame is still small, repeat  opening the tank slower.... 

    The device will turn off the tank if it is not hooked up...  If you turn it on, and the hose is not pressurized, it thinks the tank is not hooked up, and on occasion will let a small amount of gas through the line... basically it is a pressure regulator with a shut off in it somehow..... 

  4. dward51

    dward51 Master of the Pit OTBS Member

    Great point Dave, I forgot about that possibility.

    This reminds me of one more possibility and it's related to your gas tank and not the smoker/cooker.

    I have one 20 pound LP tank for my big Weber gas grill that seems to accept a little more gas at my local refilling station.  They fill by weight and always seem to slightly overfill this one tank.  It took me a while to figure out why my burners were very week and then going out.  I had a lot more yellow flame than normal when it did this also. Problem was the regulator was icing over.

    This was caused by the overfilled tank.  It would let some liquid fuel into the regulator body.  The regulator is designed to deal with the fuel in a gaseous state and normally liquid fuel should not be entering the regulator (it should be converting to gas in the tank not the regulator).  As the liquid fuel vaporized, its is an endothermic reaction and will freeze the regulator while sucking heat to flash to a vapor.  I noticed frost on the outside of the regulator even though it was summer and this was my first clue.  Ended up using a hair dryer on high to keep the metal regulator body warm so I could burn off enough gas to lower the liquid level in the tank.  After that that tank worked fine.   That one tank has done this twice so apparently the float valve that is "supposed" to prevent overfilling is off just a little.

    Have you noticed any frost forming on your regulator? It should be silver colored, disk shaped with a red knob on it. It's on the hose near the fuel tank. If so, try the hair dryer trick and see if it will let you burn some off.  It may work after that.
    Last edited: Mar 16, 2013
  5. daveomak

    daveomak Smoking Guru OTBS Member SMF Premier Member

    Speaking of overfilled tanks....  on vacation once..... the guy at the gas station thought he'd do me a favor....  It was an old tank, and he closed the vent hole on the tank and kept filling....  He said,"I gave you extra".....  well I got to camp and hooked the tank to my BBQ and liquid/gas ran out the burner and set the whole thing on fire....   Wouldn't have been so bad except I had a 15' hose hooked to the BBQ.....   took forever for that propane to gas off and it was shoving more liquid until it was all vapor....

    Once liquid comes out, everything freezes.... then more liquid...  It's darn near a never ending experience.....  

    Sounds like the shut off / float lever, what ever it is called, in your one tank is bad.... Trade it in and tape a note to it....  Overfilled tanks are a bad deal....  Even guvmint regs can't fix that type thing..... HAHAHAHA

    The new tanks, I think they will expel liquid without being hooked to a hose or regulator if turned upside down.... not sure.... I think they have a weighted lever / switch inside the tank... upside down, the thing don't work....   out comes the liquid.... 

    Well, good luck with it... check the burner for spiders etc also... between the inlet orifice and the burner ring...   may be a blockage....  

  6. dward51

    dward51 Master of the Pit OTBS Member

    Yeah, I need to swap that one out with a pre-filled one.  I hate to do it because the pre-filled ones around here are only 60-70% full and they charge more than the hardware store does to actually fill mine while I wait/watch.  I probably need to check the certification stamp date also,  might be a 1970's tank with a POL valve placed on it.

    Ok, more back on track of the thread.....

    Jim, let us know what you find out (spiders, etc... and if the regulator was icing up).
  7. I have a Masterbulit Pro dual burner model. I had the same issue. I found a spider web in the burner pipe. I cleaned it out. All is good.

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