1994 Johnson 120 barely charging... head scratcher?

[ptbrakefield]

Went to crank my 94 120 Friday of last week... it turned over a few times and then nothing. The battery was dead. I charged the battery and the engine started right up. I didn't have my volt/ohm meter with me, but the diagnostic on my depth finder said it was putting out 11.5 volts at idle. I revved it to 3000 (it was in the water... it stays in the water) and it went up to 11.6. The tach works fine.

Am I looking at stator, or rectifier? Both? Neither? Something else I need to look at and report back on? We're going back to the lake tomorrow and will be there for the rest of the week.

 

[oldboat1]

Think it might be time to replace the battery -- have it tested.

 

[racerone]

Why not test the battery charging part of the stator.

 

[oldboat1]

11.6 v at 3k rpm is low. Assuming wiring is shiny bright, battery is strong, stator output is up to specs, 13.8 or 13.9v would be expected, imo.

 

[ptbrakefield]

Think it might be time to replace the battery -- have it tested.

Brand new this year...

 

[racerone]

What ohms do you read ( 0.7 ohm ) on yellow wires.----And yellow wires to ground?----Brand new battery ???----I would still have it tested.----A quick and free service at most shops !

 

[ptbrakefield]

Why not test the battery charging part of the stator.

I've seen lots of bench testing vids... can I check it on the motor? I assume you can access the wires. Am I looking for it to be an open circuit?

 

[oldboat1]

Burnish the battery wires until bright before making tests.

 

[ptbrakefield]

What ohms do you read ( 0.7 ohm ) on yellow wires.----And yellow wires to ground?----Brand new battery ???----I would still have it tested.----A quick and free service at most shops !

Been storming here in central Alabama since late Friday... finally have some decent weather, so we'll head down around noon. I'll check the wires then.

The shop that works on my boat put the battery in a month or so ago. I'll pull it after checking other stuff and get it tested. The boat's in the water.

 

[racerone]

Stator can be checked on the motor with flywheel in position.----Just find the wires.

 

[Vic.S]

Went to crank my 94 120 Friday of last week... it turned over a few times and then nothing. The battery was dead. I charged the battery and the engine started right up. I didn't have my volt/ohm meter with me, but the diagnostic on my depth finder said it was putting out 11.5 volts at idle. I revved it to 3000 (it was in the water... it stays in the water) and it went up to 11.6. The tach works fine.

Am I looking at stator, or rectifier? Both? Neither? Something else I need to look at and report back on? We're going back to the lake tomorrow and will be there for the rest of the week.

Check the continuity and resistance of the stator. See the CDI Electronics Troubleshooting Guide for the correct value.

Also following the CDI guide check the output volts from the stator coil. You will need a peak reading meter or a DVA attachment for a normal multimeter to do this

If you do not have a peak reading meter or a DVA go straight to checking the rectifier ( you will need a multimeter with a diode check setting for this but most have this).

You should be able to find the 6th edition (2014) of the CDI guide on line.

 

[ptbrakefield]

Just got back to wifi from the lake...

I charged the battery off of the boat. Checked the voltage and it was 12.7. I let it sit overnight and checked it the next morning: 12.5. That afternoon it was still at 12.5. I put it on the boat, cranked it, and got 13.8 at the battery, and 14.1 on my depth finder going down the lake (but it reads a little low). I let it sit overnight in the boat, and the next morning it still read 12.5, so there is no parasitic drain from the electrical system.

I have no clue why it was dead that one day... I will continue to monitor through the weekend, though, just in case. I also ordered a battery cutoff switch, which I probably needed anyway. I'm also going to install a deep cycle battery and switch to it when we anchor to run the radio, anchor lights, etc., again just to be on the safe side.

So, for those of you who said battery, thanks... and for those who chimed in with test procedures, those will certainly come in handy in the future if I have more problems.

Thank you all!