Specifications

2
56
Starter Motor
Conditions Affecting Starter Motor Performance
1. Bound or seized starter motor bearings.
2. A shorted, open or grounded armature.
a. Shorted armature (wire insulation worn and
wires touching one another) will be
indicated by LOW or NO RPM.
b. Open armature (wire broken) will be
indicated by LOW or NO RPM and
excessive current draw.
c. Grounded armature (wire insulation worn
and wire touching armature lamination or
shaft) will be indicated by excessive
current draw or NO RPM.
3. A defective starter motor switch.
4. Broken, damaged or weak magnets.
5. Dirty or binding starter drive.
Troubleshooting
If a starting problem is encountered, check the
engine to eliminate it as the cause of the problem.
Check the engine for freedom of rotation by
removing the spark plugs and turning the crankshaft
over slowly by hand.
Test the battery, see page 47.
Engine Cranks Slowly
a. Additional load affecting performance (see
above).
b. Faulty electrical connection (battery circuit).
c. Discharged battery (also see alternators).
d. Dirty or worn starter motor commutator,
bearing, weak magnets, etc.
e. Worn brushes or weak brush spring.
f. Wrong oil viscosity for temperature
expected.
g. Battery leads too long or wire too small.
h. 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. Starter clutch slipping.
d. Battery faulty or damaged.
e. Reverse rotation due to incorrect motor
polarity – all motors rotate counterclockwise
viewed from pinion gear.
Starter Motor Spins But Does Not Stop
a. Defective starter switch.
b. Defective Solenoid
Testing
A fully charged 12 volt battery (5) is required.
Remove starter motor from the engine to test.
1. Assemble starter motor to test bracket.
2. Clamp test bracket in vise, Fig. 51.
CAUTION: Do not clamp motor housing in a vise
or strike with a hammer. Starter motors contain
ceramic magnets that can be damaged if the motor
housing is hit, deformed or dented.
3. The DC Shunt (6) MUST be installed on the
NEGATIVE (-) battery terminal as shown in
Fig. 51.
4. Insert RED test lead (4) into V receptacle in
meter. Connect to RED post terminal on shunt.
5. Insert BLACK test lead (3) into COM receptacle
in meter. Connect to BLACK post terminal on
shunt.
6. Rotate selector to 300mV position.
7. Connect a lead from the POSITIVE (+) battery
terminal to the connector on the starter.
NOTE: If an optional starter switch (2) is NOT USED
connecting the POSITIVE lead will activate
the starter motor.
8. Activate the starter motor. Note reading on
meter and RPM on tachometer (1).
NOTE: Take reading after meter stabilizes (approxi-
mately 2 – 3 seconds).
9. A starter motor in good condition will be within
specifications listed.
• Minimum RPM – 6500
• Maximum Amperes – 35
For Briggs & Stratton Discount Parts Call 606-678-9623 or 606-561-4983
www.mymowerparts.com