Keep in mind two very important troubleshooting
the igniter plug. If the igniter is not heard, stop the
commandments:
motoring and check the turbine plenum drain for the
presence of fuel. If some fuel comes from the drain, the
Components are changed not as a means of
ignition circuit is likely to be faulty, or carbon has
troubleshooting but as a result of trouble-
fouled the igniter plug.
shooting.
The ignition circuit electrical check includes the
Locate and correct the problem; don't just treat
igniter plug, ignition unit, leads, oil pressure switch,
the symptoms.
and the 35-percent switch. If no fuel comes from the
drain and there are no igniter sounds, the fault is
T h e f o l l ow i n g d i s c u s s i o n r e l a t e s t o
probably something common to both fuel and
troubleshooting on the basis of system knowledge and
ignition--the two-stage oil pressure switch.
analysis.
Remember, this switch operates on oil pressure;
therefore, the oil pressure should be checked before
No Response When the Start Switch Is
changing the switch.
Activated
If igniter sounds can be heard while the unit is
Be sure the recommended starting procedures are
motoring, and excessive fuel runs out the plenum drain
followed when trying to start the unit. The start relay is
when the unit is shut down, the fuel flow divider
a heavy-duty relay and makes a relatively loud sound
(within the fuel shutoff and drain solenoid valve)
when energized. Listen for the sound of the relay and
should be checked. This can be done by disconnecting
starter motor while actuating the start switch. If the
the secondary fuel manifold at the valve and installing
relay "clicks" but the starter is silent, the starter or a
a hose from the port to a catch bucket. Disconnect the
current limiter relay coil in the starter relay is faulty. If
ignition unit and motor the engine. A slight amount of
the starter runs but the turbine is not turning, remove
fuel should leak from the hose. If a continual flow is
the starter and inspect the clutch. If the starter clutch is
noted, the flow divider is leaking within the fuel
found to be in order, inspect for a sheared pinion drive
shutoff and drain solenoid valve and allowing too
shaft between the accessory section and the
much fuel into the combustion chambers. This causes
compressor section. This can be checked by rotating
an overly rich mixture, which prevents combustion. If
the turbine axial wheel at the exhaust outlet while
the valve is operating properly, check the auxiliary fuel
o b s e r v i n g g e a r m ove m e n t t h r o u g h t h e s t a r t e r
shutoff solenoid valve at the fuel control for internal
mounting hole. If the gears do not rotate with the
leakage.
turbine wheel, the engine must be disassembled and
repaired by an authorized repair activity.
If no fuel drains from the fuel shutoff and drain
solenoid valve when power is secured, check the
If the starter relay does not "click," verify that all
solenoid valve for proper operation. This can be done
switches are in their proper position, in proper
by disconnecting the fuel line coming from the fuel
sequence, at the proper time. If all switches are correct,
control to the valve and checking the cracking
an electrical control component or circuit is defective.
pressure. If the cracking pressure is within limits,
Check the start switch, fuses or circuit breakers,
check the electrical circuitry to the valve via the oil
turbine inlet door switch, air select (output air) switch,
pressure switch, control relay, and the 110-percent
pilot transfer switch, enclosure cannon plugs, and
contacts in the centrifugal switch. If the electrical
wiring.
circuitry is in order, replace the fuel shutoff and drain
solenoid valve.
Starter Turns the Turbine But There Is No
Light-Off (Combustion)
Unit Flames or Booms on Light-Off
Listen to the unit's motoring action. Screeching or
A booming light off or flames emitted from the
thumping sounds may indicate internal bearing,
exhaust are caused by excessive fuel flow into the
compressor, or turbine wheel and seal failures. These
combustion chamber at light off. This condition,
affect the starter's ability to turn the engine fast enough
known as a hot start, may also be caused from
for ignition (insufficient oil pressure). Also, a weak
admission of fuel into the combustion chamber before
battery may be at fault. If the battery is sufficiently
there is sufficient airflow for combustion. Premature
charged and no rubbing sounds are heard, listen near
admission of fuel can result from a leaking fuel shutoff
the combustion chamber for the "cracking" sound of
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