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Author Topic:   Evinrude Gray Wire
montauk steve posted 05-22-2006 09:02 PM ET (US)   Profile for montauk steve   Send Email to montauk steve  
After looking for all the electrical items that can go wrong with the tachometer and charging system, I am now lost.

1983 Evinrude 90-HP 2 stroke

This past weekend I had the motor running in the neutral position, gave her some gas and put the RPM up there. I checked the terminals coming off the motor to the battery, measured battery volatge at 12.3V. Turn the motor off and checked for continuity on the stator, the YELLOW and YELLOW/GRAY wires. I am good there. I also checked each to ground and there is no continuity. Checked the resistance on the YELLOW and YELLOW/GRAY wires and it reads 0.7 Ohms

Take the boat out on Saturday night for a little fishing and testing. Fish finder says 12.2V so does the FLUKE multimeter while running at 10-15 mph.

What gives with the charging unit? This would eliminate the rectifier and voltage regulator, right? But the stator is still good using the information that I found here. I don't have a service manual yet. Yes, I do need one, but getting laid off wasn't in the plan either. If anyone can hook up that section of the manual that would be fantastic. :)

Also before I took the boat out, I checked the gray tach wire, at idle I get 5-VAC. This is across the grey and the ground on the tachometer. Raised the RPM and the voltage went down. Is this right? This would eliminate the reasoning that the rectifier is bad right? So maybe a new tachometer then?

When I check the rectifier do I need to remove the wires from the little panel that they are all connected to?



jimh posted 05-22-2006 09:48 PM ET (US)     Profile for jimh  Send Email to jimh     
The signal on the tachometer lead (GRAY) is not a steady voltage. It will be an alternating current with a peak voltage of near the battery voltage, perhaps slightly higher, and a low close to ground. The frequency of the signal changes with the engine speed. Different meters will measure it differently. I really don't know what sort of reading you'll get there with your Fluke multi-meter. It depends a lot of the characteristics of the meter.

The acid test for the charging circuit is to see the voltage at the battery increase when the engine is started and charging current is flowing. If you are only getting 12.2 Vdc at the battery while the engine is running--that sounds low.

I am not familiar with the particular model of engine you have. Is the rectifier separate from the regulator? Your Fluke probably has a diode test function built into it. You can use that to check the four diodes in the rectifier if it is a typical full-wave bridge. If it is an integrated assembly with the regulator, I don't know how you check it with an ohmmeter.

Your check of the stator coil sounds reasonable. A reading of 0.7 ohm for the winding of the coil sounds good. No leakage to ground sounds good. I agree with your assessment--the stator coil checks good with an ohmmeter.

montauk steve posted 05-22-2006 10:04 PM ET (US)     Profile for montauk steve  Send Email to montauk steve     

Thanks for tach info. its a fluke 73. it probably measures peak to peak on the AC side.

as far as the rectifier goes i think i will take the leads off and test it that way to see.

I will also test the tach signal again.

the battery is a new optima blue top cranking battery. out of the box it had 12.3V

the rectifier is separate from the voltage reg.

one thing is when i first got the boat i couldnt get her started and wasted the battery on trying to start. i then connected a battery charger to it and proceeded to plug it in and then swith it to the "start motor" selection and used that to start her the very first time. Just saw that thread and i guess i could have fried the rectifier that way.

seahorse posted 05-23-2006 12:39 AM ET (US)     Profile for seahorse  Send Email to seahorse     

Check the Optima recommendations for charging amperage and voltage. Your '83 charging system only shorts the yellow stator wire to ground when the voltage gets close to 16V. The other side keeps charging, regardless. If the gray tach lead is ever connected to the yellow stator wire instead of the yellow-gray, the tach will go to zero whenever the regulator shorts out the yellow lead to reduce the voltage. Back then your charging system was designed for heavy duty wet-cell batteries that could have the water replenished, and maintenance-free batteries should not have been used.

Later model Johnsons and Evinrudes had full voltage control in the water cooled regulators so both maintenance-free batteries and AGM sealed batteries could be used.

montauk steve posted 05-23-2006 03:36 AM ET (US)     Profile for montauk steve  Send Email to montauk steve     

hmmm... about the voltage getting close to 16V. Now i checked the motor number and since there is power T/T there is a voltage regulator. I am going to assume that its is regulating voltage to 14.5-15V max. I dont know the specs on them but from this link here:

bsmotril finds the test method and max voltage for the reg.

maybe you are speaking of something else, if you are let me know. i would like to know for the better of the CW.

optima site says the following

"13.8 to 15.0 volts, 10 amps maximum, 6-12 hours approximate."

that is for both dual purpose and the cranking battery, both, which i have. only running one as of right now.

i know that the following may not be accurate but its safer for me to look at the gps/ff while heading to the spot, rather than asking the gf to drive the boat that fast while i walk around the deck trying to probe the battery. when i check the battery to the ff they were right on. and when i crank the battery the ff shows a drop in the voltage due to the draw that the motor creates to start.

anyone else want to chime in??



seahorse posted 05-23-2006 08:02 AM ET (US)     Profile for seahorse  Send Email to seahorse     
Your voltage regulator only controls part ( 1/2 wave ) of the charging output, as back 23 years ago we did not need the better regulation of the battery voltage.

You can add a new style water-cooled full-wave regulator to the top aft of your engine block should you ever want to make the system more accurate and less hazardous to maintenance-free batteries.

The part number is 585195 for just under $100. Your present 1/2 wave regulator costs more, $125.

Chuck Tribolet posted 05-23-2006 08:50 AM ET (US)     Profile for Chuck Tribolet  Send Email to Chuck Tribolet     
If you need to measure voltage accurately underway, make up
a cord with bannana plugs on one end for the voltmeter, and
a cigarette lighter plug on the boat end.

Look ma, no hands.


bsmotril posted 05-23-2006 09:26 AM ET (US)     Profile for bsmotril  Send Email to bsmotril     
I just ordered a regulator for my 84 Johnson 100HP Commercial last week, and it cost me $270 from the dealer. It has not come in yet, so I can't check the part#. I was seeing voltage measured at the battery vary from about 14V to 16+ volts. Did the newer style regulator you mentioned come standard on 1984 motors?

montauk steve posted 05-23-2006 05:27 PM ET (US)     Profile for montauk steve  Send Email to montauk steve     
one more thing about the tach.

when i first start the motor, the tach reads 500-700 rpms. then goes down from there during running to the fishing spots. from all that i have read, that is the common rectifier problem.

Now the next question is, if the rectifier is bad then the there will be no output voltage from the charging system right?

found a rectifier for around 35 shipped.

What do you guys do with the batteries after a day on the water? pull the terminals off so that there is no potential drain on the battery or on/off switch which does the same thing?

thanks again


seahorse posted 05-23-2006 07:12 PM ET (US)     Profile for seahorse  Send Email to seahorse     

Your 100 hp has the same charging system, 6 amp w/o trim and 10 amp with trim. You can save a few bucks and use the less expensive regulator which is good up to 12 amp systems. You will need to reroute the wires a bit compared to the $200+ regulator. It's easy to see how with the service manual.

montauk steve posted 05-24-2006 01:37 AM ET (US)     Profile for montauk steve  Send Email to montauk steve     

what service manual do you have? the seloks or the actual OEM evinrude one? thanks


seahorse posted 05-24-2006 03:35 AM ET (US)     Profile for seahorse  Send Email to seahorse     
The factory manuals are the only accurate ones and have a lot more information and illustrations. Remember that the manuals were correct at the time of printing, but over the years, manaufacturer's change parts, procedures, and suppliers which can make the book obsolete in some cases.
That is why dealers have to invest in service training and keep up with service bulletins. By the same token, do you want your doctor to treat you using only the medications and procedures used in 1984, or be kept up to date and trained in the latest innovations for your health?

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