Hit a rock now mower won't run.

broknsymetry

I was mowing my yard this morning and everything was going well. Then I hit a landscaping rock hidden in the grass. The mower started running rough then quit. I can now pull start it and runs fine for just a second or two but then cuts out. I checked the blade and it looks ok. I’ve not had a chance yet to pull the cover to check the flywheel key but would that be broken if it still starts? Otherwise what could be the issue?

egeezer

broknsymetry
Taking a guess, the key or pin in the flywheel could have sheared, allowing the flywheel to shift back and forth and throwing off the magneto timing when you start it. I’m not familiar with the electronic ignition on some mower engines, just the ones where the flywheel has a magnet to energize the mag coil at somewhere before piston TDC.

(Are you sure you didn’t run out of gas, I have a story about a guy who worked on a car for a whole weekend with that as a cause 😃 )

broknsymetry

egeezer Taking a guess, the key or pin in the flywheel could have sheared

Yeah, put some on order earlier.

egeezer (Are you sure you didn’t run out of gas, I have a story about a guy who worked on a car for a whole weekend with that as a cause 😃 )

First thing I checked. I too have a similar funny story. When I first started riding motorcycles, my first long test run of my new (used) bike I ran out of gas in the middle of crossing a long bridge across the St. Johns river in Jacksonville. So I pushed the bike the rest of the way across and for about another half mile before I finally remembered the bike had a reserve tank. 🙂

Guy54435

broknsymetry I agree with the sheared or deformed key assessment, if it took out the flywheel key it probably sheared or deformed the key for the blade attachment point.

egeezer

Guy54435

Good point, check both blade and flywheel keyways. The flywheel may be hard to remove if the shaft is burred. There’s an adapter that holds the blade that is keyed to the engine crank shaft. The key may have buggered the keyway on the crankshaft when you hit the rock. You may also find that the blade adapter is broken too. Have your Dremel tool available to clean up the shaft if needed.

Some mowers only have biscuit keys. I think that’s a design flaw.

Astyanax

broknsymetry I ran out of gas in the middle of crossing a long bridge across the St. Johns river in Jacksonville. So I pushed the bike the rest of the way across and for about another half mile before I finally remembered the bike had a reserve tank. 🙂

It’s a nice, wide river up there! It’s mostly just a swamp filled with gators down here near its source great for air boating. 🙂

https://www.sjrwmd.com/waterways/st-johns-river/