MerCruiser 305 CID (5.0L) Service Manual page 265

STARTING SYSTEM
Testing / Replacement
1. Using continuity meter, connect test leads as shown, and connect 12 volt battery with
jumper leads as shown.
2. If no meter movement is present, replace solenoid.
Testing
Starter Motor Voltage
Always test the voltage at the starter motor to ensure that it is getting at least 9.5 volts during
cranking.
IMPORTANT: Voltage below 9.5 causes excessive heat build up, which can damage
the starter motor and weld the starter solenoid contacts together.
1. Check the battery to ensure that it is not at fault.
2. With a fully charged battery, connect the voltmeter positive (+) lead to the terminal on
the starter solenoid.
3. Connect the voltmeter negative (–) lead to the starter motor case. Ensure that there is
good metal contact to prevent a false voltage reading.
4. Crank the engine over for about 10 seconds and record voltmeter reading.
5. A reading of 9.5 volts or more shows the starter motor is getting sufficient voltage.
NOTE: If the starter is getting at least 9.5 volts and the engine is not cranking as it should,
remove all the spark plugs and try turning the engine over by hand. If the engine turns over
freely by hand, the starter motor could have a problem.
6. A reading below 9.5 volts suggests voltage loss between the battery and the starter. Re-
fer to "Testing Starting System For Voltage Drop"
Index
Page 4A-10
SERVICE MANUAL NUMBER 24
72630
90-861327--1 OCTOBER 1999