Lawn mower still runs after pulling spark plug wire??
 

My lawnmower has been pretty much a POS since I bought it (Craftsman 6.75 HP mulching self propelled). It's never mulched right, leaves clumps, bogs down easily, and the drive broke a couple years after I bought it. Well today, the dead man switch went, so there wasn't a way to shut it down, so I pulled the spark plug wire thinking that would kill it immediately. It ran for a good 45-60 seconds after!!

How can that be?

Gererator inside?

hot spot due to carbon build up? also by pulling plug no flywheel/ blade brake action?

Its dieseling.

http://en.wikipedia.org/wiki/Dieseling

Interesting. We had an old Pinto wagon when I was a kid that used to diesel, but it ran really crappy while it was dieseling so I didn't think about that w/ the lawn mower, as it seemed like it was running normally.

Thanks! Makes sense.

Pull the head and clean off all the carbon on the piston.

Decent used ones show up on Craig's List all the time for cheap. I bought one 3 years ago for $60.00 and it has been perfect.....FWIW.

Not sure why it didn't stop after you pulled the plug wire......is it named Christine by any chance?

<object width="640" height="360"><param name="movie" value="http://www.youtube.com/v/hnZK0Zv05FU?version=3&amp;hl=en_US"></param><param name="allowFullScreen" value="true"></param><param name="allowscriptaccess" value="always"></param><embed src="http://www.youtube.com/v/hnZK0Zv05FU?version=3&amp;hl=en_US" type="application/x-shockwave-flash" width="640" height="360" allowscriptaccess="always" allowfullscreen="true"></embed></object>

Use a window spray bottle to spray some water in the intake while its running.

probably a Briggs & Stratton engine.............just a major POS.

Steve

73 911 T MFI Coupe, Aubergine

Sounds like it's time for a new one. Treat yourself.

yea that's where i'm leaning right now. breaking open my lawn mower engine just doesn't sound as fun as working on the 911....

i think it's gonna go out on the curb the night before trash day and be a gift for the guys that cruise the neighborhood for metal before the trash trucks come....

If the plug wire is still near the plug it can jump the plug. Dieseling may be a issue but with the low compression and light flywheels its pretty rare.

buy it a new spark plug
I bet the old plug is covered in carbon
and is acting like a glow plug

Bingo. There has to be some source of ignition on a gas engine and if the plug is not doing it, something else is.

Look for a Toro super-recycler with personal pace rear drive. If you can find one, the 6.5 GTS aluminum deck models. Search around on craigslist, you should be able to find one in the $100-150 range.
I recently picked one up from a colleague who was moving and didn't want to take it with him. By far, it's the best walk behind mower I've ever used, and I've used hondas, lawn boys, other toros and snappers. It does an awesome job mulching and the drive is phenominal; it's very natural and will go as fast as you want.

I pulled the head, scraped the carbon off the top of the cylinder and the inside of the head (not too bad, but I don't know what 'too bad' is for a 1 cylinder engine), and replaced the spark plug, which also didn't look too bad.

She's running like a top now :). Thanks for the inputs.

This is the usual suspect......glad you got her going again!