Possible causes for burner failures:
1. Power to the burner blower motor (fuse, burner switch, wiring or motor overload)
2. No fuel (clogged filter, clogged line, or simply out of fuel) **this might be easy to overlook**
3. Flow switch is not functioning
4. Solenoid or coil that activates solenoid
5. Fuel pump or coupler to fuel pump
6. Electrodes or transformer or both
7. Clogged fuel nozzle or incorrect pattern due to partial clog (atomization incorrect)
8. Air / fuel mixture is misadjusted (air damper & / or fuel pressure)
9. Incorrect voltages
10. Incorrect fuel
11. Air flow through coil incorrect (clogged coil)
12. Thermostat or high limit switch is not working
13. Blower motor damaged or not working (not turning due to motor or squirrel cage is damaged or stuck)
Troubleshooting a burner:
1. Check for positive airflow from the stack when burner switch is activated (eliminates power issue to burner and fan damage)
a. also indicates fuel pump should be running if coupler is intact as blower motor activates the fuel pump
b. if airflow is not present, check voltage to blower motor, or sticking blower motor or squirrel cage. If there is no voltage the switch, a fuse or wiring is faulty.
2. If airflow is present: check for fuel flow by clamping the line to the filter for a few seconds and look for movement of fuel. You may see that the fuel is churning in the filter without clamping, however unclamping the line after a few seconds will show a “rush” of fuel into the filter.
a. if fuel flow is present this eliminates the coupler and the fuel pump.
b. if fuel flow is not present: check the coupling shaft from blower motor to fuel pump. If coupler is ok, pump may be damaged.
3. If fuel and airflow is present: check the coil on the fuel pump side. This is a wired box like fixture, usually oval on one side and flat on the other side, but may be square as well. It has a hole in the center and is held on with one nut (usually 10mm). Disconnect and check voltage to the coil. Run unit with burner “on”. Stick a screwdriver through the hole of the coil. When the trigger is depressed the coil should magnetize and hold the screwdriver.
a. if the coil activates and holds the screwdriver, and releases when trigger is disengaged all safety switches have been eliminated (i.e. flow switch & / or thermostat).
b. if coil does not activate at all, either voltage to coil is bad (check for 110v or 12v depending on system). If voltage is present coil is bad.
c. if voltage is not present, check flow or pressure switch for proper function. Check thermostat or high limit for proper function. Perform a ohms or resistance test on wiring to, from & through switches to determine which one or ones are faulty. If neither switch is faulty (either mechanically or electrically) then power from the main switch should be checked
4. If fuel flow, airflow, switches voltage, and coil activation is present: check for solenoid activation by disconnecting the line from the fuel pump to the burner assembly. This is usually a copper tube with 11mm / 7/16” fittings on either side. Run unit and depress trigger with coil installed.
a. if fuel comes out under pressure the fuel pump officially is eliminated, and the likely cause of failure is a clogged fuel nozzle.
**WARNING** the transformer operates at up to 25,000 volts. Electric shock or death is possible when testing live voltages and therefore is not recommended by anyone not certified. If anyone is not certified and is not comfortable working with live voltages STOP here and take the entire unit or just the transformer to a certified technician for proper testing.
5. If fuel flow, airflow, switch voltages, coil activation, and nozzle are verified: check the transformer for operation. **This test can be done at any point in the troubleshooting process!**
a. simple test of the transformer can be conducted by waiving an insulated bar such as a screwdriver over the opened transformer springs. An arc should visually appear across the
springs. If the arc is weak or non existent, then the wiring to the transformer should be checked for proper voltage (either 110v, 220v, or 12v depending on system).
**WARNING** electric shock or death possible by conducting this type of test. All precautions should be adhered to (proper grounding, insulated tools, insulated boots etc.) This test should NOT be conducted by a non certified technician or anyone unfamiliar with high voltage equipment, STOP and take the entire unit or just the transformer to a certified technician for proper testing.
b. if voltage is present to the transformer, the transformer needs replacement.