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I have a Toro 124k02-0110-b1 mower.
It has been working fine all season. There has been a small fuel leak which only occurs while running.
Anyways, suddenly, it wont start. When I pull, it spins, but the engine doesn't turn over and does not seem like it is trying. Plenty of fuel in the tank. It worked last week so I assume the fuel is good. I checked and changed the spark plug, I can visibly see the spark. I also changed the air filter. I removed the screw/bowl of the carburetor. There is fuel at the bottom. I can see through the hole in the screw but clean it out anyways so the hole is bigger now.

We have fuel, air, spark so I would think it should start.

I am not exactly sure which direction the fuel flows in the carburetor. If there is fuel in the bowl, does it mean there is fuel/air getting to the cylinder?

I'd appreciate any recommendations

No not necessarily. Make sure the orifices in the bowl nut are clean and open. If they are. What can happen is the seat will move down in the well where it sets thus raising the float and shutting the flow of fuel entering the carb. bowl. If that is what has happened the toe of the float will be elevated and this shuts the fuel flow to the bowl. The float with the carb inverted with the float up the float should sit level. If that is the problem you will need a 398188 needle and set kit and 796610 bowl gasket if needed. If you have a good compressor you can blow the seat out and drop the new one in with the smooth side up and press it in with a good smooth punch. Oh yes putting a little oil on the seat before you drop it in the well will help it press in easier.

I see, I'll check the seat/needle.
the bowl and nut are very easy to get off so I did that first.

eng3 said:

We have fuel, air, spark so I would think it should start.

I am not exactly sure which direction the fuel flows in the carburetor. If there is fuel in the bowl, does it mean there is fuel/air getting to the cylinder?

Click to expand...

No. Fuel has to get from the bowl to the cylinder, and there's many a slip 'twixt cup and lip.

Clogged passages/jets.
Vacuum leak.
Intake valve seat loose.
Intake valve not opening enough.
Valve timing off.
Choke open.
Throttle not open.

It's not just fuel/air/spark. Fuel and air have to be in the right proportion, which varies with engine temperature and load. You need vacuum and compression, valves have to seal, and everything has to be timed right. The spark has to be strong enough to jump the resistance of compressed air, which is several times stronger than when you ground the plug to the block in open air. And of course, even if you get a little cough, the engine won't start if it's under load.

hlw49 said:

No not necessarily. Make sure the orifices in the bowl nut are clean and open. If they are. What can happen is the seat will move down in the well where it sets thus raising the float and shutting the flow of fuel entering the carb. bowl. If that is what has happened the toe of the float will be elevated and this shuts the fuel flow to the bowl. The float with the carb inverted with the float up the float should sit level. If that is the problem you will need a 398188 needle and set kit and 796610 bowl gasket if needed. If you have a good compressor you can blow the seat out and drop the new one in with the smooth side up and press it in with a good smooth punch. Oh yes putting a little oil on the seat before you drop it in the well will help it press in easier.

Click to expand...

Before you go to all the trouble of any of this spray a little gum out carb clean in the carb and see if it runs and dies. If it does them you will know it has a carb issue.

So I pulled the cover off and noticed a small rock holding the throttle (valve) partially closed. Maybe 20% closed? hard to tell, not much.
I thought maybe this was the cause so I tried starting the engine but no joy.

I wasn't sure where exactly where I should spray the carb spray to test, I just shoved it through where the air goes in as far as I could to try to get it in the engine. I did maybe a 1-2 second spray.
Pulled and it started with a puff of black smoke coming out the front (which is strange since exhaust comes out the side). To my surprise it stayed running and did not die (at least for 30sec before I gave up).

I then went ahead and started it again and mowed the law with no issue.

Still not sure exactly what the issue was/is.

eng3 said:

So I pulled the cover off and noticed a small rock holding the throttle (valve) partially closed. Maybe 20% closed? hard to tell, not much.
I thought maybe this was the cause so I tried starting the engine but no joy.

I wasn't sure where exactly where I should spray the carb spray to test, I just shoved it through where the air goes in as far as I could to try to get it in the engine. I did maybe a 1-2 second spray.
Pulled and it started with a puff of black smoke coming out the front (which is strange since exhaust comes out the side). To my surprise it stayed running and did not die (at least for 30sec before I gave up).

I then went ahead and started it again and mowed the law with no issue.

Still not sure exactly what the issue was/is.

Click to expand...

Could be the primer system. with the air filter off pump the primer and look in the throat of the carb and see if you can see fuel coming out of the main nozzle. If not you may have to replace the air cleaner base part no.795259. They sometime warp and it won't pump air into the carb bowl and push the fuel out the main nozzle.

hlw49 said:

Could be the primer system. with the air filter off pump the primer and look in the throat of the carb and see if you can see fuel coming out of the main nozzle. If not you may have to replace the air cleaner base part no.795259. They sometime warp and it won't pump air into the carb bowl and push the fuel out the main nozzle.

Click to expand...

Might be. This morning, it wouldnt start again, spraying some carb cleaner allowed it to start up.

The air cleaner base part has a metal piece blocking the hole on the side going in but I can fit the straw from the carb cleaner can down it. However I can't see inside very well. I tried looking through the gap and it doesnt looking like anything is coming out when I press the primer

eng3 said:

Might be. This morning, it wouldnt start again, spraying some carb cleaner allowed it to start up.

The air cleaner base part has a metal piece blocking the hole on the side going in but I can fit the straw from the carb cleaner can down it. However I can't see inside very well. I tried looking through the gap and it doesnt looking like anything is coming out when I press the primer

Click to expand...

It Could be the primer bulb as well make sure it is not cracked. Gas won't just gush out but you should be able to see it.

hlw49 said:

It Could be the primer bulb as well make sure it is not cracked. Gas won't just gush out but you should be able to see it.

Click to expand...

I see no cracks. I found a youtube video demonstrating it and I don't see anything coming out so I guess it is probably that.

I seem to be able to find a replacement for as cheap as $10 so it seems like a pretty simple thing to just try.

eng3 said:

I see no cracks. I found a youtube video demonstrating it and I don't see anything coming out so I guess it is probably that.

I seem to be able to find a replacement for as cheap as $10 so it seems like a pretty simple thing to just try.

Click to expand...

The primer bulb can look perfect and still be worthless.

Those air filter housings are known for warping
When they do the priming system fails because the air leaks out the back of the housing
Some times 2 gaskets fix it some times you have to replace the housing.
Another good idea in a design studio that is a total failure on the lawns.

So reporting back after the winter, I replaced the primer bulb (actually the whole Air Filter & Primer Base) and it still won't start. The chances of getting a bad one seems low but I'm not sure what else it could be. It is hard to tell if fuel is making it in as it is hard to see.

Reminder, mower wouldn't start towards the end of the last season. Spraying some carb cleaner in the cylinder caused it to start to the assumption was that the primer bulb was bad. Didn't really have a chance to test it til recently.

eng3 said:

It has been working fine all season. There has been a small fuel leak which only occurs while running.

Click to expand...

Read what you wrote here again. Read it out loud.

Fuel leaks can burn the mower or garage slash house to the ground. Put new fuel line on her or repair the leak asap.

eng3 said:

I am not exactly sure which direction the fuel flows in the carburetor. If there is fuel in the bowl, does it mean there is fuel/air getting to the cylinder?

Click to expand...

No. Jets could be plugged up as well as the carb needle stuck closed. Agree with the other guys.

take it to the local mower shop. The engine has a problem with the fuel system. It may also have a loose head based on the cloud of black smoke in the wrong spot.

Does it surge when running or run quite well ?

bertsmobile1 said:

Does it surge when running or run quite well ?

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Perhaps when it first starts (hard to tell right now), otherwise runs well

sgkent said:

take it to the local mower shop. The engine has a problem with the fuel system. It may also have a loose head based on the cloud of black smoke in the wrong spot.

Click to expand...

That only occurs when starting by spraying carb cleaner into the cylinder, not on a normal start.

slomo said:

Read what you wrote here again. Read it out loud.

Fuel leaks can burn the mower or garage slash house to the ground. Put new fuel line on her or repair the leak asap.

No. Jets could be plugged up as well as the carb needle stuck closed. Agree with the other guys.

Click to expand...

Maybe the a fuel leak could burn up the mower. Don't see how it could burn a garage/house down. The outside of the fuel line is dry so I don't think it is from there. I was going to get some of the fuel dye additive to try to track down where its coming from. Obviously from somewhere fuel only flows when the engine is running. Don't see the connection to the start issue.

a gallon of gasoline has the explosive force of just under 100 sticks of dynamite. You really don't want ANY fumes or leakage in the garage. When gasoline burns it melts the tank and lets the gasoline flow all over everything. Spraying it with water just spreads it -and if things are hot the steam just makes a big cloud of flammable droplets. Think grease fire in a pan in the kitchen when someone pours water on it. You do not want a mower on fire in the garage.

eng3 said:

Don't see how it could burn a garage/house down.

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Some people like me, park mowers in the garage. Some people have cars in their garage. I have several gas cans in there too.

Put away a hot mower in a 110 degree garage in peak summer. Think about it.

eng3 said:

Obviously from somewhere fuel only flows when the engine is running.

Click to expand...

Lots of mowers have gravity fed tanks. Some larger ones have fuel pumps. Just saying.....

You should be able to wipe your fingers around every end of a hose or connection and find a fuel leak.

Like I said before, replace ALL of your fuel line and be done with the leaks. Unless your tank has a leak? We are talking a couple bucks here.

parking a mower in a garage was not the issue, what was said was do not park it in the garage if it is leaking fuel because one does not want a mower fire in the garage. The OP said no big deal. 100 sticks of dynamite is a big deal and any spark can lite the fumes, water heated, wall switch etc.. Fix any leaking hoses or park it in an open space away from anything that can become a secondary file if a few drops of fuel falls on a hot muffler etc.. I don't see what there is to debate about.

slomo said:

Lots of mowers have gravity fed tanks. Some larger ones have fuel pumps. Just saying.....

You should be able to wipe your fingers around every end of a hose or connection and find a fuel leak.

Like I said before, replace ALL of your fuel line and be done with the leaks. Unless your tank has a leak? We are talking a couple bucks here.

Click to expand...

I wiped my finger along the hose where it sticks out and it is always dry. I assumed this is the lowest part so fuel would drip down. That is why I am thinking the leak is not coming from there.
I'll open it up and take a closer look.

sgkent said:

a gallon of gasoline has the explosive force of just under 100 sticks of dynamite. You really don't want ANY fumes or leakage in the garage. When gasoline burns it melts the tank and lets the gasoline flow all over everything. Spraying it with water just spreads it -and if things are hot the steam just makes a big cloud of flammable droplets. Think grease fire in a pan in the kitchen when someone pours water on it. You do not want a mower on fire in the garage.

Click to expand...

slomo said:

Some people like me, park mowers in the garage. Some people have cars in their garage. I have several gas cans in there too.

Put away a hot mower in a 110 degree garage in peak summer. Think about it.

Click to expand...

As I "think about it", I still don't see how my garage/home would burn down/explode. I have lots of dangerous things in my garage, car, gas cans, paint, etc. My furnace is in a closet in there too. As I've stated, the mower only leaks fuel while it is running. I clean it off after I mow the lawn and store it in the garage and it does not leak anything, outside is bone dry, nothing on the floor either. All my containers are capped. Even if I had a small pool of gasoline on the floor and parked my mower on top, it would not be hot enough to ignite gasoline fumes. It's not like I'm smoking in there. Maybe at most, I could start a pool of gasoline on fire if I for some reason dropped an open flame right there, but it wouldn't just explode. Maybe if I had an open container and there was no ventilation. I'd need to be incredibly unlucky to happen to have the perfect gasoline fume and oxygen mixture in the garage to cause an explosion. If it were that easy, we'd have exploding garages all over the place.