Yanmar 1GM10 Shop Manual Download

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TROUBLESHOOTING

Ammeter

Voltmeter

Starter motor

open circuit or a loose connection. If the engine does not
start, replace the starter solenoid.

Starter spins but does not rotateflywheel

Remove the starter. See Chapter Nine.

2. Check the starter pinion gear. If the teeth are chipped

or worn, inspect the flywheel ring gear for the same prob-

lem. Replace the starter

ring gear as required.

If the pinion gear is in good condition, disassemble the

starter and check the armature shaft for corrosion. See
Brush Replacement, Chapter Nine, for the disassembly
procedure. If no corrosion is found, the starter drive mech-
anism is slipping. Replace the starter with a new or rebuilt
marine unit.

Starter will not disengage when start switch is released

This problem is usually caused by a sticking solenoid or

defective start switch, but the pinion may jam on the fly-

wheel ring gear on an engine with many hours of opera-
tion.

NOTE

low battery or loose or corroded battery

connections can also cause the starter to re-
main  engaged  with  the flywheel ring  gear:
Low  voltage  at  the  starter  can  cause  the
contacts  inside  the solenoid  to chatter and
weld  together;  resulting  in  the  solenoid
sticking in the

Loud grinding noises when starter runs

This can be caused by improper meshing of the starter

pinion and flywheel ring gear or by a broken overrunning

clutch mechanism.

Remove the starter. See Chapter Nine.

2. Check the starter pinion gear. If the teeth are chipped
or worn, inspect the flywheel ring gear for the same prob-
lem. Replace the starter

ring gear as required.

If the pinion gear is in good condition, the overrunning

clutch mechanism in the starter may be defective. Replace
the starter with a new or rebuilt marine unit.

Starter Solenoid Resistance Tests

Check the starter solenoid using the following resis-

tance tests:

UTION

Disconnect the

battery cable be-

fore performing resistance tests.

Refer to Figure

and connect an ohmmeter lead to the

S terminal of the solenoid. Connect the remaining ohm-

meter lead to the metal body of the solenoid. The ohmme-

ter should indicate approximately one ohm or less.
Replace the solenoid if the ohmmeter indicates infinite re-
sistance (no continuity).
2. Refer to Figure

and connect an ohmmeter lead to the

S terminal of the solenoid. Connect the remaining ohm-
meter lead to the M terminal of the solenoid. The ohmme-
ter should indicate approximately one ohm or less.
Replace the solenoid if the ohmmeter indicates infinite re-
sistance (no continuity).

Starter Motor No-Load Current Draw Test

If troubleshooting indicates that the starter motor may

be defective, use the following starter motor no-load cur-
rent draw test to determine if the starter motor is in accept-
able operating condition.

To perform the test, the following equipment is needed:

an ammeter capable of measuring 0-1 00 amps, a voltme-
ter, a vibration tachometer and a fully charged 12-volt bat-
tery. Minimum battery capacity is 70 amp-hours for
and two-cylinder engines and 100 amp-hours for
three-cylinder engines.

Remove the starter motor from the engine. Securely

fasten the motor in a vise or other suitable holding fixture.

Using a heavy gauge jumper cable, connect the amme-

ter in series with the positive battery terminal (Figure

4).

Connect a voltmeter to the battery.