Lawnmower won't start; now what do I do?

[JesseJ]

Only thing I could think of when I read the thread. . .
Buy Electric

[majortom]

had a problem with my lawnmower too this spring, was able to run it a few times, then around the 2nd or third cut of the season, it quit running. Would start no problem, just wouldn't stay running. and really bogged down soon as ya hit some grass.

Drained last years gas, and refueled with new, same problem.
Wound up having to remove the Bowl by the carb, had a hairball of grass plugging it. Remove one nut from underneath to get at it.

Runs like a champ ever since...


Basically just like this:

http://wiki.answers.com/Q/Why_does_a...fter_it_starts

[byebye_cable]

I feel sick. That lawnboy 2 stroke would have lasted another 20 years easy.

The spark plug looks kinda black. Removing it/holding it in my hand and pulling the cord I can hear the click-click of the plug but can't actually SEE the spark. Unless I touch the business end THEN I see a spark & get mildly shocked. Spraying WD40 into the piston, replacing the plug & pulling the cord is normally how I get small engines underway when there's trouble, but that is not working this time, not even a splutter. Replace the plug?

I'm not handy enough to take the engine apart.

[stampeder]

Was he aware that it required premix instead of plain gas?

[ScaryBob]

I would replace the plug. That's a common problem with small engines, especially two strokes. Drain the carb bowl too in case there was water in the gas.

[byebye_cable]

Originally Posted by stampeder

Was he aware that it required premix instead of plain gas?

The actual story is a little more complicated.
- Neighbour borrowed & ran out of gas
- Refilled with plain gas
- Finished cuttting lawn
- Then my daughter got it out & started it again & started cutting OUR lawn
- Started making a "funny noise", died & smoked.
- Alert Daddo

I'm SURE the neighbour didn't realize - I don't have the heart to tell her either.

I'll try the plug after work, fingers crossed. I hate wasting things.

[Jake]

I imagine the engine overheated from lack of lubrication. The piston expanded from the heat rubbing the rings then the piston against the cylinder walls. This produced the smoke, the crank encountered an increase in resistance and snapped the connecting rod. I speak from experience. In my case it was a 4-stroke tipped up on its side. The cause (lack of lubrication) ended with the same results.

If when you pull the cord it is easier than normal (almost purring) then chances are the rod is no longer connected to anything.

You can test my theory by removing the plug and placing a screwdriver into the cylinder until it touches the piston. Slowly pull the cord to see if the piston head moves the screw driver up.

[byebye_cable]

Originally Posted by Jake

You can test my theory by removing the plug and placing a screwdriver into the cylinder until it touches the piston. Slowly pull the cord to see if the piston head moves the screw driver up.

It moves!!

Perhaps there is hope. Excellent diagnostic btw, ty. New plug next.

[Jake]

You can also check for compression. Lay the plug in the threads but don't thread it in. Just made sure there is a seal. Pull the cord moderately slow and see if you get a pop as the plug is expelled from the the cylinder head. If the valves are toast most of the air will escape there or around the piston rings. The fact it is not seized is a miracle.

[byebye_cable]

Getting ready to throw the white towel.

I don't get this though - with the new plug I see the spark PLAINLY - but even when I spray WD40 into the piston, replace the plug, pull the cord - no even a splutter.

Originally Posted by Jake

You can also check for compression. Lay the plug in the threads but don't thread it in. Just made sure there is a seal. Pull the cord moderately slow and see if you get a pop as the plug is expelled from the the cylinder head. If the valves are toast most of the air will escape there or around the piston rings. The fact it is not seized is a miracle.

For me this was inconclusive - plug fell out - but if I put my finger over the hole I do feel compression/depression when pulling the cord. Mostly depression

[57]

Are these the mowers with reed valves? Perhaps one's burnt out/shot.

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

Did you check the magneto? Is it generating a spark? - you can test this with the spark out of the engine but with the spark wire connected, with the spark close to the motor - wear heavy gloves to prevent a shock to you.

Make sure the air filter is clean and check to see if gas is going into the carburetor - you can usually see this if you press the "prime" button. Gas valve open? Gas in tank?

[Danster]

What colour is your spark? Is it blue or redish?

[byebye_cable]

Originally Posted by 57

Did you check the magneto? Is it generating a spark? - you can test this with the spark out of the engine but with the spark wire connected, with the spark close to the motor - wear heavy gloves to prevent a shock to you.

Saw an arc from the plug to the motor - I'm guessing that's good.

Originally Posted by 57

Make sure the air filter is clean and check to see if gas is going into the carburetor - you can usually see this if you press the "prime" button. Gas valve open? Gas in tank?

Removed the sponge & hit the prime button a few times - fuel did spray into the thing (carb?).

Originally Posted by 57

Are these the mowers with reed valves? Perhaps one's burnt out/shot.

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

I read this & perhaps one is - but (in my mind at least) this would not explain why there's NOTHING when i spray WD40 (or gas) myself into the cylinder, replace the plug and pull the cord.

I do feel some compression/depression when placing my finger in the plug hole & pulling the cord. It's not clear to me if it's the appropriate amount though. Is it possible that the fuel I spray in to the cylinder manually IS actually igniting in the cylinder - but SO much pressure is escaping thru the valve (or whatever) that I don't hear a "splutter" even for a moment when the fuel ignites? I keep thinking I should hear something - but maybe I would not.

Thank You.

[byebye_cable]

Originally Posted by Danster

What colour is your spark? Is it blue or redish?

I would say there is a tinge of blue. Definately not redish.

[Danster]

Blue is good. It indicates high voltage.

As far as WD40 in the cylinder, you don't do to good with it. You actually "clean" the sidewalls of the oil needed to lubricate and help the rings in creating compression.

WD40 is a great water displacer. It doesn't have the same flashpoint as gas so the putter you are waiting for might not be as big as you want it to be.

What I would do is this: Remove the air cleaner adn where the carb throat is, about the size of a quarter, just cover that part with the cushy part of the base of your thumb with the spark plug removed. Pull the cord at the same time. It will (should) suck up any gas right into the cyclinder. At the same time, you should feel and see gas on your thumb.

After 3 or 4 pulls, replace the spark plug and try it. If it will start, that is where it will.