1990 Evinrude 100 HP (E100STLES) rectifier question..........

[JimInAlabama]

I suspect I may have a charging problem, it's been charging fine but last week on the water had to jump start off trolling battery, and then noticed the voltage reading on sonar unit was only showing 9 -10 volts with engine running, in the past it's always been around 13.5. I slow charged the battery and checked with meter at battery terminals, the voltage was 10 - 11.5 running with no amp draw, 9 with livewell pump turned on. Have not tested the battery but it's a decent quality marine cranking battery only 4 months old and once charged holds the charge well.

The tach has had issues since I got the boat this spring, it only works intermittently for short periods at lower rpm.* I installed a known good tach and got same results so I know there's been something going on with the rectifier or the wiring.

Two questions:

I haven't done any ohm checks yet, I'd like to get all the info together before I decide whether to even try to troubleshoot this myself.* (I can't afford to take it to a marine shop now and I don't have an ammeter for running load test.) Is there a reliable "poor man's" check using only a standard volt/ohm meter?

Another question .......... The parts breakdown shows both a rectifier AND a rectifier/regulator.* The OMC manual describes ohm checks for both, but the rectifier check is shown for 88 model only, does my motor have both a rectifier AND a rectifier/regulator, or only the latter?
Thanks,
Jim

 

[Haffiman]

Re: 1990 Evinrude 100 HP (E100STLES) rectifier question..........

No working tach and no charging - most likely the rectifier.
To be sure, ohm between the yellow wires from stator. If resistance, most likely OK, change rectifier.
Your engine has a combined regulator and rectifier. Unfortunately you have to remove the flywheel to change it.
Be aware that the most common reason for failure, except for running without battery connected, is impeller failure
and open thermostats. That creates an air pocket on top of the cylinder, and it looses the cooling.

 

[JimInAlabama]

Re: 1990 Evinrude 100 HP (E100STLES) rectifier question..........

No working tach and no charging - most likely the rectifier.
To be sure, ohm between the yellow wires from stator. If resistance, most likely OK, change rectifier.
Your engine has a combined regulator and rectifier. Unfortunately you have to remove the flywheel to change it.
Be aware that the most common reason for failure, except for running without battery connected, is impeller failure
and open thermostats. That creates an air pocket on top of the cylinder, and it looses the cooling.

Just what I needed, I appreciate it. I'll check stator resistance but I agree, I suspect a bad rectifier. I hate it because I've heard that ignition/charging systems on these old motors tend to go bad in a domino effect once you start having problems! Are there other things I should do from a maintenance standpoint while I've got the flywheel off?

Thanks again for your help.
Jim

 

[Haffiman]

Re: 1990 Evinrude 100 HP (E100STLES) rectifier question..........

Check that it is dry and clean and no signs of melted insulation on any coils. If so, your stator is going to be changed as well.

 

[Sprky]

Re: 1990 Evinrude 100 HP (E100STLES) rectifier question..........

The simple way would be to put your volt meter on the battery. Start the motor and bring the rpm's up and see if it exceeds 13.0 volts. Anything less than 13.0 and regulator/rectifier is shot.

Chris

 

[AEROCOOK]

Re: 1990 Evinrude 100 HP (E100STLES) rectifier question..........

Just what I needed, I appreciate it. I'll check stator resistance but I agree, I suspect a bad rectifier. I hate it because I've heard that ignition/charging systems on these old motors tend to go bad in a domino effect once you start having problems! Are there other things I should do from a maintenance standpoint while I've got the flywheel off?

Thanks again for your help.
Jim

I had the same issues with my 1988 110 hp Johnson and the ohms test told me very quickly that the problem was the rectifier. I installed a new one and all is well, tach works again and the battery charges.
FWIW that was 3 years ago and (touch wood) I haven't had any more electrical issues. I was told by a marine technician that you cant run these motors without a battery hooked up or you will fry something. He thought thats what might have killed my rectifier but since it was already blown when I bought the motor I cant say for sure.

 

[JimInAlabama]

Re: 1990 Evinrude 100 HP (E100STLES) rectifier question..........

No working tach and no charging - most likely the rectifier.
To be sure, ohm between the yellow wires from stator. If resistance, most likely OK, change rectifier.
Your engine has a combined regulator and rectifier. Unfortunately you have to remove the flywheel to change it.
Be aware that the most common reason for failure, except for running without battery connected, is impeller failure
and open thermostats. That creates an air pocket on top of the cylinder, and it looses the cooling.

I suppose overheating could be a definite possibility, it's been hotter than blue blazes here this summer. Are there other symptoms that would indicate faulty thermostats, or a way to troubleshoot without actually opening it up and physically inspecting? The VRO was disconnected when I got it, not sure if that was done correctly or not, I've never checked to see if the overheat alarm even works.

 

[Haffiman]

Re: 1990 Evinrude 100 HP (E100STLES) rectifier question..........

The best instrument is an IR temp gun.
Check the temp balance on the cylinder banks, must be even. Thermostats are about 65C (145F), temp below that on idle, you have thermostat problems.