boat parts

Outboard ignition parts for Mercury Mariner outboard motors. Power pack, stator, timerbase, regulator.


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Page 35 - Index - Page 37
Voltage Drop Measurement

    The use of an ohmmeter to test a conductor or switch contacts for their condition is not always the best tool to use. In many cases, it is preferred to use a volt drop test to make sure the conductor as well as the connection is in good condition.

    Start by using a good digital auto-ranging volt meter capable of reading 1/10th of a volt. The use of an auto-ranging meter will allow for more accurate testing without damaging the meter due to an incorrect range setting.

    Remove the spark plug wires form the spark plugs and connect them to a spark gap tester and remove the emergency stop clip as well. This prevents the engine from starting and also reduces the chance for you to get shocked by the ignition system.

    Before testing, remove and clean all battery cables and connection points.
Testing the Positive Battery Cable to the Engine

  1. Select the DV Volts position on the meter.
  2. Connect the Red (Positive) lead of the meter to the positive battery POST.
  3. Connect the Black (Negative) lead of the meter to the starter solenoid terminal where the positive battery cable is connected.
  4. Using a remote start switch, activate the starter solenoid to spin the engine and observe the reading on the meter. A reading above 0.6V is an indicator of a bad cable or bad connection.
    (A) If the meter reads above 0.6V, move the Black lead of the meter to the positive battery cable terminal on the starter solenoid and retest. If the reading drops to below 0.6V, the cable connection is bad.
    (B) If the meter still reads above 0.6V, move the Black lead of the meter to the positive battery cable terminal on the battery and retest. If the reading drops to below 0.6V, the cable is bad or undersized.

    Service Note: A bad power connection to the ignition or battery charging system can be found by connecting the Black lead of the meter to the power connection of the ignition system or charging system and working your way back to the battery positive post. At no time should you see a reading above 1V.
Testing the Negative Battery Cable to the Engine

  1. Select the DV Volts position on the meter.
  2. Connect the Black (Negative) lead of the meter to the negative battery POST.
  3. Connect the Red (Positive) lead of the meter to the engine block where the negative battery cable is connected.
  4. Using a remote start switch, activate the starter solenoid to spin the engine and observe the reading on the meter. A reading above 0.6V is an indicator of a bad cable or bad connection.
    (A) If the meter reads above 0.6V, move the Red lead of the meter to the negative battery cable terminal on the engine block and retest. If the reading drops to below 0.6V, the cable connection is bad.
    (B) If the meter still reads above 0.6V, move the Red lead of the meter to the negative battery cable terminal on the battery and retest. If the reading drops to below 0.6V, the cable is bad or undersized.

    A bad ground connection to the ignition and battery charging system can be found by connecting the Red lead of the meter to the ground connection of the ignition or battery charging system and working your way back to the battery negative post. At no time should you see a reading above 1V.
Page 35 - Index - Page 37