Turkey fryer is burning rich w/ yellow flame and cannot be regulated to blue by air mix plates

Yellow flame makes soot or carbon and an excess of poisonous carbon monoxide and whatever is causing it is likely to worsen.

Basically there is too much gas for the amount of air available - a dirty burner will produce yellow flame as will dust, fluff and spider webs blocking the air hole into the mixing chamber. Such stuff can be dragged deep into the mixing chamber so it is best to remove the burner assembly in order to ensure it is completely clean.

Yellow flame is incomplete combustion. This can be due to poor air inlet or mixture. It is normally related to low air into the burner mix. Lint build up or grease can cause vents to reduce or block. A yellow flame is rich in co2, which has a direct link to higher co levels.

Orange or yellow gas flame indicates air is not being mixed with the gas before burning.

The pilot burner has air holes to allow air to mix with the gas for efficient blue flame burning.

The air holes are probably blocked if the flame is approximately the usual length or longer. If it is significantly shorter it indicates the gas pressure to the jet is reduced.

The heat exchanger might be a result of the yellow flame but not the cause of it burning yellow. I would guess it is the amount of air being mixed with the gas. Most burners have a slotted metal air mixture ring on the front of the burner near the brass orfice, you are calling a jet. There is a locking screw to release the ring so it can turn to adjust the amount of air being mixed with the gas. If this doesn't fix the yellow flame it could be a gas pressure problem that could be the external regular in the gas line. Not sure if you are talking about the pilot flame or the burner flame or both? A tech should know how to adjust the air mixture.

You should find an air mix adjustment for that burner. Try opening it a little, to allow more air. A yellow flame indicates too rich a mix.

The adjustment is probably behind the knob for that burner.

Vaporized propane sounds just like air coming through a hose. Turkey fryers use a different regulator than a standard barbecue which uses a low pressure -- 11" water column displacement. Pressure for a BBQ is measured in displacement because LP pressure is very low, less than half one pound PSI. Turkey fryers use a higher pressure so more gas is able to feed to the burner but the regulator diaphragm adjusts because of the adjustment wheel. However, before determining the regulator needs to be replaced, adjust the air shutter on the venturi and ensure the orifice is clear. LP must be mixed with air in the burner in order to burn but if the shutter is open too much we can hear air-flow and too much air can definitely cause that sound and cause flames to blow out. We have a video at you---e showing the adjustment with too much air blowing-out the flames. First check your connections and orifice to make sure there are no leaks or impediments. Second restart the burner with the air shutter almost closed and continue making adjustments -- while burning if possible. If neither of those work replace the pressure regulator. Most people will initially say replace the regulator but they do not go bad as often as many think; a regulator is only a open space that limits him much gas can travel through at any time.

Low gas pressure will produce low flame quality (yellow flame).
Check and remove any dirt or soot on burner holes, and orifice
Burner flame not going inside the fire tube could be due to soot or carbon build up inside the fire tube blocking the flame path, check the inside of the fire tube, if considerable amount of soot is seen, better have them removed.
Yellow flame will cause a lot of problem on fryers if not corrected as soon as possible.
If you have doubt on your gas regulator, better have a qualified service technician to check it.

Check your propane tank first; is it getting close to being empty? Check where the hose connects to the burner, there should be an air adjustment there; it looks like a rotating disc with two big holes on either side, this is turned when the burner is lit to adjust the amount of air mixing with the gas. If it's all the way open, you have a yellow flame, if it's closed all the way you have a blue (but weak) flame. Try adjusting that and if that doesn't work, try a different regulator...it is rare a regulator could cause this but it could cause it; just use that as your last resort.

Make sure you are using an adjustible high pressure regulator. Make sure there are no obstructions insde the burner tube or burner holes.

try adjusting the air flow on the burner.