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422 flashing lights after shutdown

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  • 422 flashing lights after shutdown

    Serviced the heater, new burn pot & ring etc and runs fine until temp is reached and shuts down. All lights flash like out of fuel.

    plenty of fuel, swapped main board, air pressure switch and temp wire.

    Any advise is appreciated as I can not find any reference in service manual about this.

    thank you

  • #2
    I will try replacing the carburetor, not sure what else it could be.


    • #3
      Watch the flame when the stove is running. Either the flame is strong and steady when the lights start to flash, or the flame diminishes then the lights come on. Strong flame when lights come on indicates flame sensor issue. Weak or diminished flame is a fuel issue.


      • #4
        If the flame sensor is making contact with flame ring it will cause this. Mine would do this occasionally so I cut the flame sensor off just below the bend and put it back in. It doesn't happen as often now. My flame ring doesn't seem to be warped so I don't know if it and the flame sensor were actually making contact or if carbon was bridging between them causing the problem. Have you checked and cleaned all the filters? The fuel pump also has a screen on the bottom of it. A couple years ago my heater would run constantly on high and not keep the house warm. After checking everything else I could think of I pulled the pump and there was lint on the screen preventing enough fuel from getting to the pot to put out enough heat to keep the house warm. I cleaned it with a paper towel then soaked it in vinegar for a couple hours. The heater has ran fine since.
        Last edited by FordMan59; 02-24-2020, 11:51 AM.


        • #5
          I agree with Fordman on cutting the flame sensor off at the bottom bend. We have done this as a standard procedure for fifteen years now. If you look at a Toyo flame sensor, it does not hang down past the edge of the burner ring. If you do cut it, be sure to cut it right at the bend. The screws that hold the flame sensor bracket should be tightened the same, as not to force the rod in or out.


          • #6
            I replaced the carburetor and the fire valve and my issue went away.

            the 422 was fully serviced, new burn pots/ring. Fan bearings, combustion was oiled and replaced the o-ring along with cleaning the carburetor and filter and needle valve.

            the heater ran perfect until it went through shutdown, and turned off - that’s when all light would flash like out of fuel.


            • #7
              How high above the set temp does the stove run before it shuts down? Also, does the flame cut out completely very shortly after the Status Lights go out?


              • #8
                Msearcher, Did you get your M422 going again?


                • #9
                  Yes, replaced the carburetor