Lanair MX200 - Manual (Page 50)

Section 14 - Troubleshooting
46
Burner fuel pressure gauge reading hints:
Fuel gauge fluctuates (jumps):
s Water/Anti-freeze in fuel.
s Leak in suction line plumbing.
s Air in fuel, refer to Troubleshooting Chart Item B.
s Quad ring seal for the nozzle may be damaged.
s Seal in adapter block may be worn or damaged.
s Fuel pressure regulator seal leaking or dirty when using a by-pass regulator.
s Suction line strainer plugged or dirty.
Reading gradually decreases:
s Fuel pump output decreasing.
s Fuel viscosity decreasing.
s Orifice in nozzle is wearing.
Reading gradually increases:
s Fuel pump output increasing.
s Fuel viscosity increasing (cold fuel, and/or gear lube).
s Orifice in nozzle is becoming plugged.
Reading drops to –0- PSI when the burner is off.
s Dirt between the diaphragm and the seat in the by-pass regulator when using a
by-pass regulator.
s Dirt between the plunger and the nozzle seat.
s Leak in the plumbing connections.
s Leak in the pre-heater assembly (damaged or missing o ring).
s Fuel pre-heater switch is off.
Steps to check the air operated fuel valve:
s Disconnect the two transformer wires from the terminal block in the burner.
s Jump the cad cell circuit (refer to pages 44-45).
s Disconnect the fuel supply pump orange wire from the terminal block inside the
burner.
s Set the dial indicator as shown on the diaphragm piston.
s Zero the dial indicator.
s Start the burner so that the air valve opens.
NOTE: The dial indicator should read +.015 to .050, which references the diaphragm
piston travel.
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