SECTION 6: ELECTRIC STARTER
6-1
GENERAL INFORMATION
The starter motor utilizes a solenoid, similar to an automobile starter, to
assist in pinion gear engagement. When the starter motor is activated,
the pinion gear engages a ring gear attached to the engine flywheel
and cranks the engine.
Figure 6-1. Starter Motor
TROUBLESHOOTING
NOTE: If a starting problem is encountered, the engine itself should
be thoroughly checked to eliminate it as the cause of starting
difficulty. It is a good practice to check the engine for freedom
of rotation by removing the spark plugs and flywheel guard and
turning the crankshaft with a socket and ratchet or breaker bar,
to be sure it rotates freely.
*
WARNING: Do not rotate engine with electric starter while spark
plugs are removed unless using a compression gauge. Arcing
at the spark plug ends may ignite the gasoline vapor exiting
the spark plug hole.
ENGINE CRANKS SLOWLY:
a. Additional load affecting performance (see note above).
b. Discharged battery.
c. Faulty electrical connection (battery circuit).
d. Discharged battery (see alternators).
e. Dirty or worn starter motor commutator, bearing, weak magnets,
etc.
f. Worn brushes or weak brush spring.
g. Wrong oil viscosity for temperature expected.
h. Battery leads too long or wire too small.
i. Battery too small.
ENGINE WILL NOT CRANK:
a. Faulty safety interlocks.
b. Discharged or defective battery.
c. Faulty electrical connections.
d. Faulty starter motor switch (open circuit).
e. Open circuit in starter motor.
f. Brushes sticking, etc.
g. Faulty solenoid.
STARTER MOTOR SPINS BUT DOES NOT CRANK ENGINE:
a. Sticking pinion gear due to dirt.
b. Damaged pinion or ring gear.
c. Battery faulty or damaged.
d. Incorrect rotation due to
reversed motor
polarity – all motors rotate
counterclockwise viewed from pinion gear.
e. Damaged solenoid
STARTER MOTOR SPINS BUT WILL NOT STOP:
a. Defective starter switch.
b. Solenoid stuck engaged.
TEST EQUIPMENT
DIGITAL MULTIMETER:
A digital multimeter (VOM) may be used to read volts, ohms, amperes
and test diodes (rectifiers), Figure 6-2.
NOTE: The Digital Multimeter is equipped with two fuses to prevent
damage to the meter in the event that the input limits are exceeded.
If the meter displays a reading of 0.00 when testing DC output, check
fuses in meter. Refer to VOM operators manual for procedure for
checking fuses.
Figure 6-2. Digital Multimeter
6
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