No start on older Briggs and Stratton mower

[Oldtom]

Good Evening. I have a Murray mower made in 2004. Model number 225113X92A Briggs engine number 123K02 0230 E1 040319 FB. I stopped the engine to refuel by releasing the safety lever and it will not restart. A Harbor Freight spark tester shows no spark when the starter rope is pulled. The safety lever prevents the engine from turning when released, does it also cut the ignition? I want to check all no cost things before spending 50 dollars on a magneto.

Thanks in advance for any advice

 

[old1]

Yes it cuts the spark. Sometimes those cables stretch and don't pull quite far enough to release the stop switch. Try grabbing the cable itself and pulling it a little further, then see if it will start.

 

[Donald]

If it's old enough to have a magneto it's probably not worth fixing if that means a new magneto.

 

[Linctex]

The "Magnetron Ignition" almost never fails!

Find out where the tiny black ground wire is shorted out to.....

 

[69GTX]

I went through a similar issue back in June. My control cable/start/kill lever had been yanked enough times that it was no longer properly cycling that ground connection from the magneto...it was the last thing I finally considered...lol. I stuck a piece of paper in the gap between the 2 metal pieces (ie ungrounded) and it started right up. I ended up having to use some electrical tape to reorient the cable in proper alignment to the kill switch so that it would get back a full range of motion. Some cable tie wraps were replaced too since if the cable is free to move it won't cycle fully. As mentioned above the ground wire from the magneto to the kill switch ground can be bad too. You can check continuity from the magneto metal case back to the kill switch. When I contacted a local dealer they said the magneto's almost NEVER fail. Failures are almost always the Carb. Though if it's electrical, it's usually either the ground wire or switch itself. The stuff I found on line was full of misinformation. For one they said if your magneto reads over 5-7 K ohms it's failed. Mine read around 8800 ohms so I assumed it was failed. It wasn't. It was the operation of the ground switch. If you have some rust or gunk built up on that switch wire brush it down. Ensure the 2 halves properly open and then make contact with each other when the bail level is cycled.

I troubleshot everything electrical on my mower. Learned a lot...that I forgotten over the years. My problem came on over a month or so once the cable housing got damaged. The mower would just stop running in the middle of a job...to the point where eventually it wouldn't start at all. When you test the spark plug for a spark ensure you ground the case of it to a good mower ground....and even then it might not be very visible.

My old thread

New magneto's if needed would cost $32-$40. I'd bet there are a lot of used ones on junk mowers that are just fine.

 

[eljefino]

Take off the starter cowl, three little bolts. You'll see the operation of your kill switch/ brake lever and its failure will be intuitive.

As said there's a little black wire that gets grounded when you release it. A little "knife blade" slides into a slot with the wire pinched in it. A little brake shoe bumps up against the flywheel, too. A young and dumb "friend" ripped all this stuff off and put a 49 cent home depot light switch in its place.

If you mess around diagnosing this, have an insulated stick you can use to knock the spark plug wire off, and practice before you start it up again.