One way is to pull the cable off the spark plug and hold the exposed end near the metal of the engine so there is a small gap, around 1/8" to 1/4". Have a second person pull the starting cord. You should see sparks jump across the gap.
Make sure the person holding the cable is holding an insulated part of the cable using only one hand and no part of their body is touching any part of the lawnmower. Otherwise, they may get a nasty shock. It took 5 to 10 minutes before I had any feelings in my arms when I got zapped.
First of all, the key is between the crankshaft and the flywheel on the top of the engine. The crankshaft is shill connected to the blade at the other end. A sheared key will not disconnect the blade.
If the key has sheared, there will still be enough friction between the flywheel and the crankshaft so that the flywheel will continue to spin when you pull the cord. The problem is that the flywheel establishes the spark timing. So if the flywheel has slipped to a different orientation to the crankshaft, then the timing will be way off.
One way to confirm before you start drastically disassembling the engine would be to pull the spark plug out and verify 1) that you still have spark and 2) you smell fuel in the chamber. If both of those are true, it is very likely that the timing is off because the flywheel has slipped out of position.
If you donāt have fuel smell, then, given your other symptom that the engine did not start unless the fuel had been in there for at least 30 minutes, then you could have some fuel system issues. do you use fuel with Ethanol in it? Ethanol will absorb water and turns into a jelly that can clog up fuel system parts like carburetors or float valves in the carb bowl. But if you do smell fuel in your cylinder, then the sheared key is a very likely root cause.
If you have the repair manual for the engine, you can probably confirm that the timing is off before you pull everything apart. I seem to recall that I did that with my mower when I had this problem.
If you pull the spark plug out, plug it back into the cable and then hold the spark plug so that the threads are touching the engine block, then you can actually see the spark plug sparking across its gap. Make sure to ground it somewhere decently far away from the spark opening into the cylinder so that you donāt ignite any fuel vapors that might come out. Hold it by the insulated cord so that you donāt get zapped the way @philso didā¦
This is the best way to check spark because you are testing the whole system end to end. I have done this alone, but it is easier to do with 2 people (one holding the spark plug while the other pulls the cord).
Yeah, after i consulted my dad, he said the spark plug was replaced last year (i didnt get any word of this) so he assumed it shouldnt be the problem.
I guess we can say this mower is stubborn, but also resilient. As far as i can tell, the blade doesnt have a single dent in it.
I did realize something. Tonight, it started on first pull. Every other time, itās usually the second or 2.5 pulls. That being 2 full pulls and on the retraction of the 2nd, you only let it go halfway back and pull it with half the normal force on the full pulls. I found that if i didnt do the .5, it would sometimes idle and wont start up again.
The symptoms that you are reporting sound a lot like a partially clogged fuel system. I have re-built several carbs over the years due to clogging and the symptoms were similar to what you are reporting.
I have not had any issues with my current lawnmower. I have used ethanol free gasoline in it since I bought it. I realize that ethanol free gas is more expensive, but it is worth it to avoid the inevitable clogging of the fuel system that comes with using ethanol gas in equipment that sits around for extended periods between running like lawn mowers.
If you are using normal gas from a pump at the gas station, it is likely that it has ethanol in it. You may want to consider switching to ethanol free if it is available near you.
Next time, check the air filter. Itās most likely a piece of sponge-like rubber you can remove by drawing out a single flat blade screw. Remove all of the dust and leaf pieces with running water. Squeeze dry. Allow to air dry an hour or two, preferably outside in partial shade. (If thereās no wind, feel free to add a fan or wait longer.) Add a teasponfull of so of motor oil, knead to spread it out, and re-install. Online sites recommend cleaning after 25 hours of operation, but I recommend twice a season if you run less than 50 hours a year. This should reduce the number of pulls.
If you have a paper filter, replacement appears to be the only option.
Added: You may want to invest a few dollars in a can of carburetor cleaner. Not only does it do what the name implies when sprayed into the carb when the filter is removed, it also serves to provide an extra starting kick for the next few minutes before it completely evaporates.
is it normal to have the gasoline leak through the cap while running? Even on a flat surface, it will leak out. The cap is tightened and has the rubber circle/guard thing.
ā¦or am i putting too much fuel?
I would say the gas we use has ethanol, i think 87?