Why is my burner flaming out?

Why is the burner flaming out and relighting so much?

The Eclipse Air Heat burner in a Milnor dryer has a string of safeties to prove before fire is enabled.  The burner uses a flame rod that needs to see pilot flame before main gas is enabled.  
When the FireEye is enabled, the pilot gas circuit is enabled and the pilot should light.  This is a sustained pilot system.  

If the lights on the FireEye turn on and go through a progression when you want a fire, then you probably have a pilot problem.  If the top light on the FireEye stays on, then the gas train safeties are ok.  If the lower lights come on and then go off and the sequence continues to repeat, you have a pilot sensing problem.  

If the burner is rectangular (The Air Heat burner) it has a flame rod in the burner. The flame rod must be engulfed in fire to sense flame.

The most common pilot sensing problem is that the pilot is too large and while it may be burning, it is not sensed by the flame rod. To remedy this, we turn down the pilot gas flow using a needle valve in the pilot gas line. This valve has a butterfly knob on it. There is a screw in the middle of the butterfly. Take that off and see the needle valve screw under it. Turn that CW to reduce the flow.

When the main gas turns on, raw fuel pushes the pilot flame forward and pushes the pilot away from the flame rod. So, less pilot gas helps keep the flame where we want it.

If you have a jet burner, the same story applies. But the sensor is a UV sensor. It must see the pilot flame at ignition and during main firing.  

If you are not igniting pilot, then check the ignitor and spark plug. Make sure you see a spark at the tip of the plug.

If you see all FireEye lights go dark when asking for heat, you should suspect a problem with the power feed to the FireEye.  This power feed comes from the Gas Train Safeties that are all in series to the FireEye.   

So, if the lights all go out, don't chase the flame rod or pilot system as the culprit.  Another one of the safeties caused the problem.  

The most sensitive safety is the burner box pressure switch.  The purpose is to prevent negative pressure in the building from sucking fire out of the back of the fire box.  But the setting pressures are very small and are easily affected by mass flow in the fire box.  When the main fire is lit the burner box pressure goes up slightly and may trip the delicate setting of the Burner Box pressure switch.  Adjust the switch to avoid this nuisance trip.