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Motor runs fine for about 15 minutes and then dies

M

mstein

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I have 3 cylinder 60hp Mercury Marine ELPTO-1996. Serial #0G313130.
I run down the lake for a while and then it just dies. I thought it was the fuel pump so I replaced it and the filter. Same result.
Once it dies it will not start again until much later.
Please advise.
 
Make sure the engine isn't overheating, when did it last have a new impeller and thermostat installed? I would be more inclined to believe that you have a stator starting to go. Get the stator tested.
 
Just replaced the impeller 2 years ago. Not sure where the thermostat is located.
I'll attach some pics. I do get low voltage messages on my fish finder.
Thanks Fitz
 

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I replaced the thermostat and the water throughput was greatly increased, but the motor still stopped after about15 minutes. I noticed the battery connection was loose and fixed that.
That may not have had any affect, but I went fishing after that and it didn't die. It wasn't a good test though. I was running it slow and not for a long time. I think it was longer than 15 minutes though.
Maybe the temperature sensor is bad.
Are there other sensors that can cause the motor to shut down?
 
I'm sure I found the problem. I noticed that the site glass tube showed a light colored oil instead of the normally black oil. Sure enough I found the oil container and said for 2 Stroke engines instead of 4 Stroke.

I'll siphon it out and fill with the correct oil. That should fix it.

Thanks for your help, Marc
 
You have a two stroke engine and the oil in site glass looks like the correct 2 stroke blue oil in the photo, so I don't have any idea of what you are talking about. Now if you put regular automotive 4 stroke oil in a 2 stroke engine at 50-1 injected mix, that could cause engine damage. Did the engine make any noises when it shut down? This is not a 4 stroke engine in the photos.
 
No noises. It just goes from running fine to decelerating very quickly to a stop.
This is a nightmare...
What also made me question the oil was the lack of smoke when idling. It was always pretty smoky.
 
stator was mentioned in the very first response, but you have ignored that suggestion. I think that's your issue if you have low battery and shutting off after a short ride.
 
Dear halbromann,

I assure you that I haven’t ignored any suggestions.
I'm an old guy and my approach to problems is to work on the easiest possible solutions first as they are usually the answer.

The fuel pump and filter looked like low hanging fruit. Just a few bolts and some tubing. The thermostat was a simple fix too.
I've never really worked on boat motors, but the stator sounded like something difficult to fix. Maybe I'm wrong. Is it an easy fix?

When I started on this little project, the wait to get the boat into a shop was about 3 weeks. That's most of the best Spring fishing season.

I starting to lean towards selling the boat. That still might be the best solution. I can't even park it here for more than 48 hrs at a time due to the HOA.

Anyway, thanks for your concern. I'll decide on a course of action soon… Marc
 
Stator is pretty expensive (Hundreds of dollars) and replacing it requires removing the flywheel. Stator generates electrical power, similar to the alternator on a car. Once the motor is started, it runs off of power generated by the stator to produce spark. Pretty sure there are test procedures you can find online to test it and the voltage regulator without removing them. Shutting off and warning of low voltage sounds like a problem with one of those components to me. Good luck and I sure hope you find a solution.
 
I removed the regulator and found that the yellow wires were burnt around the connectors. I did resistance tests on the stator and it looks good.
Now the motor won't start.
The new regulator has different wiring for the red wires.
It includes an inline fuse on the red wire which is 2nd from one side.
The red wire which is 3rd from the end, goes to the hot side of the solenoid, I believe...
There are multiple red wires on the motor and no matter how I connect them, the motor will no longer start. Do you know where the red wires are supposed to go?
Thanks for your help.
 
More information:
Looks like both red wires go to the solenoid. Will try this next.
When I said the motor doesn't start, I mean it doesn't turn over or make a sound. The trim doesn't have power either.
I'm using an AGM battery which sounds like it could be a problem in the long run.
 
I found a schematic for the regulator wiring and tried to duplicate it for the red wires in question. The main difference was that I hadn't connected the wire from the solenoid to the wiring harness.
The result was that the motor trim started working, but the motor still wouldn't turn over to start.

My Mercury 60 hp wiring is attached

Regulator at bottom of picture of the wiring attached.
Screenshot_20250528-165841.png
I'm holding the wire attached to the wiring harness.
Screenshot_20250528-175711.png
 
Well, I finally gave up and brought it into the shop. It failed the leak test on 2 of the 3 cylinders. They also said the stator was bad, but basically the motor was worn out.
Now I guess I'll disconnect the motor and try to recycle/dispose of it. I don't have a lot of money for this so I'm thinking about buying a new 25hp motor to replace it. I guess I should start a new thread for that... Suggestions for disposal and new purchases are welcome.
 
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