1994 Johnson 200 voltage

jeremyeasen

Seaman
Joined
Jun 20, 2002
Messages
72
I was test running the boat after the mechanic tuned it up had the powerhead off to replace a motor mount. In the past few weeks the voltage had been low..12.8 or so at 4500rpm as well as idle. The rectifier is only 2 years old, no tach problems, and it was maintaining above 12 volts so I let it go. I rev'd it up to 5500 just to check the carbs after adjusting and at that point the voltage jumped to 13.8...where it should be. Back to normal, but it makes me nervous when engines fix themselves. Any explanations from the experts here?
 

HighTrim

Supreme Mariner
Joined
Jun 21, 2007
Messages
10,486
Re: 1994 Johnson 200 voltage

Possible you have a bad connection somewhere, or faulty wiring. I would make all of your connections shine, take a file to them, and check your wiring for stiff spots, arcs, cuts, etc. They are hard to diagnose since they rot from the inside out. Here is a test for the battery cables.

Testing the Positive Battery Cable to the Engine

1. Select the DC Volts position on the meter.
2. Connect the Red (Positive) lead on the meter to the positive battery POST.
3. Connect the Black (Negative) lead on 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 indicates a bad cable or bad connection.
(a) If the meter reads above 0.6V, move the Black lead on 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 on 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 on the meter to the power connection of the ignition system or charging system; then 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 DC Volts position on the meter.
2. Connect the Black (Negative) lead on the meter to the negative battery POST.
3. Connect the Red (Positive) lead on 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 on 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 on 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 on the meter to the ground connection of the ignition or battery charging system; then working your way back to the battery negative post. At no time should you see a reading above 1V.
 

jeremyeasen

Seaman
Joined
Jun 20, 2002
Messages
72
Re: 1994 Johnson 200 voltage

I've checked and cleaned to bare copper and aluminum my connections recently (does not coincide with the lowered voltage) so I'm pretty confident in those connections. I will check every bit of wiring for stiff spots. Of course there may be a terminal I missed somewhere, but can anyone suggest any peripheral components to check that are related to the charging system, aside from the rectifier, that would affect the voltage in this way? Seems like bad mojo to question a motor that runs like a champ! Just like to keep things spinning like a top. Thanks for your quick reply!

I saw your full explanation for testing wiring after I posted. Thank you.
 

HighTrim

Supreme Mariner
Joined
Jun 21, 2007
Messages
10,486
Re: 1994 Johnson 200 voltage

Im not sure, is your system regulated? (ie have a regulator?) If you have an ammeter, disconnect the voltage regulator at the terminal block. Run the motor at 4300 to 4600 RPM and note the ammeter reading. SIDE NOTE: Disconnect all accesories. If the ammeter shows charge, replace regulator. If ammeter shows no charge, check rectifier and check stator windings . The rectifier is tested with the ohmmeter on HI ohms scale. The test for the rectifier and stator will be in your manual.
 

HighTrim

Supreme Mariner
Joined
Jun 21, 2007
Messages
10,486
Re: 1994 Johnson 200 voltage

Not a problem, I am the same as you and am always wondering WHY??? :) Remember though, most of these problems are connection or wiring related, but cant hurt to perform a few tests to rule out other problems. Good luck.
 
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