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 Something new... what could be the cause? 
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Post Something new... what could be the cause?
MB LT 35, Mukuni with pipes.
10 years old, 155 hrs.
Still runs good, but the other day I turned the key off, but the engine keeps running.
Install new ignition key switch and the problem still persists.
I'm still hunting, but have to shut it off with the safety kill switch being pulled.
I've check the wiring and don't find anything.

Any thoughts on what would cause this?

On a side note, I run a Lowe 17/60 with pods I put on.
New prop I run 12-13mph with 2 guys, dog, decoys, and gear. Turning 3800
Worn prop turning 3900 to 4000 and hit 15 with me the dog, decoys and gear.
I love a worn prop.

Anyway, what would cause the engine to keep running.


Tue Jan 16, 2018 10:08 pm
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Post Re: Something new... what could be the cause?
The coils aren't grounding to kill it. Check the wire that comes out of the harness that goes to ground. Also make sure the wires that hook to the coils from the harness aren't cut, and are still connected to the back of the coils. I'm not sure if bad diodes will cause this issue. Someone else can chime in on that. I think the kill switch might use the same ground, too, so check and make sure the wires are hooked to it, and aren't broken somewhere along the path.

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Tue Jan 16, 2018 10:38 pm
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Post Re: Something new... what could be the cause?

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Wed Jan 17, 2018 12:33 am
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Post Re: Something new... what could be the cause?
Could be a diode in the wiring acting up. If it were me, while your taking the cowling off and unplugging everything go ahead and do the new wiring harness and new coils. It'll run much better and give you piece of mind. You will probably be surprised at how rough your current coils look. Shouldn't take all that long, pretty straight forward too. If you want to wait until after season goes out you can just choke it to stop it.


Wed Jan 17, 2018 5:36 am
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Post Re: Something new... what could be the cause?
Thank you. This gives me a starting point.
Searched the WWW and found this I thought I would share.
https://www.briggsandstratton.com/na/en ... sting.html
I'll do a follow-up post once repaired.


Wed Jan 17, 2018 7:21 am
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Post Re: Something new... what could be the cause?
If the e-kill is shuting it down, check ground wire going to and from key switch. Sounds like Key switch is not grounding. Check for continuity to the block from key switch.

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Wed Jan 17, 2018 8:46 am
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Post Re: Something new... what could be the cause?

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Wed Jan 17, 2018 10:26 am
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Post Re: Something new... what could be the cause?
So I watched 100 videos on replacing coils and searched parts and looked at others issues and solutions.

Then today, I was getting ready to start removing the cover and I thought I'd look at at the harness connector and found no visible issues. I look over in the boat and saw the carb cleaner and started cleaning the connectors.

I start the motor and Whala, the motor turns off by the key.

I appreciate all the help and I'm already thinking of doing some of the preventative maintenance suggestion to keep this motor running.


Thu Jan 18, 2018 10:57 am
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Post Re: Something new... what could be the cause?
So I'm adding to my last post as I started to have the problem again. I went ahead and pulled the front off to get to the coils. Had to order them, so I just cleaned them up and got the rust off the magnet.

I ordered new coils and harness. The clean up did help the engine run better.

Russ, I think you might have hit it. I played with the ground wire coming out of the ignition and I think that is where the issue is it. The new harness should help.

I do have a question on the diode. I have watched a number of videos but can place where this is located.
Is it apart of the harness?


Sat Jan 20, 2018 5:14 pm
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Post Re: Something new... what could be the cause?
It's the little shrinkwrapped section of the wire an inch or 2 back from where the wire plugs into the coils.

I wasn't the only one helping. Someone else mentioned the ground wire near the ignition. Just glad you got it narrowed down.

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Sat Jan 20, 2018 7:53 pm
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Post Re: Something new... what could be the cause?
So I did it, I ordered the new wiring harness and coils. Spend most of the day with the wiring. There were a few modifications and I still need to make one more. Need the proper connector.

Coils came at 3:30 pm and they were easy to put on. I think I got them the right spacing. Seem ok.

We'll test it in the morning when I go hunting and I'll give a review.


Thu Jan 25, 2018 4:30 pm
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Post Re: Something new... what could be the cause?
Business card comes in handy when setting the gap on the coils.


Thu Jan 25, 2018 5:33 pm
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Post Re: Something new... what could be the cause?


Thu Jan 25, 2018 6:48 pm
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Post Re: Something new... what could be the cause?


Fri Jan 26, 2018 4:30 am
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Post Re: Something new... what could be the cause?
No, I don't have a feeler gauge! I'm slowly becoming a mechanic though! And need more help!

5:30am I launch the boat. Fired up the motor on the 1st turn. Motored out and the motor ran like a top. I mean it seems like it was running much smoother. I was alone with my dog and 7 dozen decoys and gear. I didn't look at the rpm in the dark, but only had it 3/4 throttle. I was hitting 13mph, for my Lowe 17/60 that was really good.

I start through the dead timber, not sure if I even hit a stump, and I lost forward push.
Now the engine is still firing away and sound good. Prop looks like it is spinning, But I can get no forward movement.

I drift to shore and start looking for an issue, all the while there is shooting going on all around us. The dog is going berzerk.

I end up walking the boat about 2 miles along the shore before the 1st hunter comes by. I flag him down and get a pullback to the dock.

Now, what could my issue be? I can tell you when I turn the prop by hand, there is little resistance.
Did I break the shaft? a crankshaft? Not sure, the prop still turns.

Any thoughts on where I should start?


Fri Jan 26, 2018 11:38 am
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Post Re: Something new... what could be the cause?
Check the keyways in the ujoint. Might have dumped a key.

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Fri Jan 26, 2018 2:38 pm
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Post Re: Something new... what could be the cause?

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Fri Jan 26, 2018 3:00 pm
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Post Re: Something new... what could be the cause?
Bingo! Russ you were right. I see the key came out. The shaft slid up 1/16 to 1/8. Not sure why or the impact of this. I don't have Reeder Guage, but I do have some key stock.

Should I worry about the shaft movement


Fri Jan 26, 2018 5:18 pm
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Post Re: Something new... what could be the cause?
I would. It's not supposed to do that.

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Fri Jan 26, 2018 6:59 pm
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Post Re: Something new... what could be the cause?
So I think I found what happened. Cause and effect.

About 3 weeks ago I noticed that a bolt had come out of the top brace on the back of the motor. As you know the motor bolts to the frame, and there are 2 bolts that connect the frame to the top of the motor. There was a gap of a good 1/4 inch. I replaced the bolt and had to crank it good to make the frame meet the engine.

I think this pulled on the u-joint fitting and with 3 weeks of vibration, it caused the Key to come out. I inspected the shaft and it hadn't moved. The coupler slid on the drive shaft out of the motor.

I think it might have been a coincidence that I just happen to change the Harness and coils.

So I replaced the Key today and I'm ready for the last day of the season.

My fingers are crossed.


Sat Jan 27, 2018 5:26 pm
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