Riding mower cranks but won't start

[viscous]

Hey everyone! Hoping you can help me start my riding mower.

It started fine a month ago, first start this spring. Ran engine 30 minutes on gas left in the tank from last fall. Shut off engine before tank ran dry. Filled gas tank with stabilized fuel that was stored over winter in a sealed container.

A month later, tried starting mower, but battery was dead. Connected buzz box with 200A engine start setting. Engine gave a couple putts, but didn't start. Tried multiple additional times, but no additional putts.

Replaced battery. Engine cranks well, but gives no sign of starting. Pulled spark plugs, which look fine, I think. One was wet with fuel. Reinstalled plugs. Emptied gas tank, replaced fuel with fresh. Engine cranks, but won't start.

What next?

 

[fantastic]

Spray starting fluid into the intake & report back.

Do you have a fuel shutoff ? Make sure it's open.

 

[viscous]

Spray starting fluid into the intake & report back.

Do you have a fuel shutoff ? Make sure it's open.

Thanks for the suggestions.

No fuel shutoff.

Don't have starting fluid on hand. Any potential ill effects of using starting fluid? The mower has never needed starting fluid before.

 

[Bailey28]

My Craftsman mower is like yours. Since owning it I have had to use a puff of starting fluid to get it to light off when cold. It will start on it's own the remainder of the day.

I replaced the vacuum diaphragm fuel pump with a new one but I still have had no luck with getting fuel to it on a cold start.

 

[burbguy82]

There might be a solenoid on the carb that has gone bad.

 

[chemman]

Do your have spark?

 

[Opelman]

There might be a solenoid on the carb that has gone bad.

I'm going to second this. I've run across several of these which just plain get stuck closed. Pop it out, free it up and mow on.

 

[TomYoung]

Thanks for the suggestions.

No fuel shutoff.

Don't have starting fluid on hand. Any potential ill effects of using starting fluid? The mower has never needed starting fluid before.

There are no meaningful ill effects of using starting fluid. If you get some noise, you know you probably have a carb issue. Not sure what equipment you have, but most carbs can be easily rebuilt with kits that usually cost less than $10

 

[nbpt100]

There are no meaningful ill effects of using starting fluid. If you get some noise, you know you probably have a carb issue. Not sure what equipment you have, but most carbs can be easily rebuilt with kits that usually cost less than $10

Make sure the choke is working as it should. You can also use carb or brake cleaner in place of starter fluid. Just do not over use starter fluid or similar. If it fires for a few seconds it tells you that you have spark and enough compression to run. Let me know where you can get a decent carb rebuild kit for $10. If it is a carb problem, I do recommend rebuilding vs. buying a cheap knock off on the internet. They are often poor quality, marked incorrectly and you get the wrong one for your application. The time you can waste on using these is insanely stupid. Just because it bolts up and looks similar does not guarantee it is the correct carb for your application.

You can easily test the anti back fire solenoid below the carb. You should hear/feel it clicking when you turn the key to on.

If the starter fluid does not give you a moment of firing then you likely have a spark issue. Do you have a spark tester?

 

[doitmyself]

Summing up a number of comments above, diagnosing a no start condition on a small (or any) engine involves checking four requirements to run:1) Spark 2.)air/fuel mixture, 3) timing, 4) compression.

Always start with the easy stuff. You can check spark at the plug by removing the plug, grounding it to the motor and pull/crank the engine and watch for a strong blue/white spark across the gap (helps to be out of the sun). Fuel - squirt a medicine dropper of gasoline into the cylinder, replace plug, and crank the engine to see if it "fires". Timing - check that the flywheel key has not sheared. Compression - tough to check even with tools, but there should be some resistance to hand rope pulling, air pressure if you hold a thumb over the spark plug hole while cranking, etc..

Depending on what you find, examine the components of all four of the above systems. Spark could be on/off switch, bad wires, bad coil, bad plug, flywheel sheared, etc.. All of this can be looked up on line nowadays.

 

[zzyzzx]

Don't have starting fluid on hand.

Have any brake clean on hand?

 

[zzyzzx]

It started fine a month ago, first start this spring. Ran engine 30 minutes on gas left in the tank from last fall. Shut off engine before tank ran dry. Filled gas tank with stabilized fuel that was stored over winter in a sealed container.

Pro Tip: If applicable, mulch leaves with the riding mower so you have an excuse to use it more off season and as a labor saving device.

 

[viscous]

You can easily test the anti back fire solenoid below the carb. You should hear/feel it clicking when you turn the key to on.

Yes, also thanks to burbguy82 and Opelman for suggesting this. Will check.

Do your have spark?

Don't know, but I did a month ago, so I would assume yes.

grounding it to the motor

How? Also, don't have a torque wrench, so can I just reinstall by feel?

There might be a solenoid on the carb that has gone bad.

Could I have damaged it by connecting the buzz box @ 200A engine start setting, then cranking?

Summing up a number of comments above...

Good ideas, thanks.

 

[doitmyself]

grounding it to the motor

How?

Like I said, you can learn everything typing your question into Google, etc. nowadays. I take for granted how much I was taught by mentors while growing up.

 

[chemman]

Do not assume anything. Just because you had spark a month ago does not mean you will have it today.

 

[fantastic]

Thanks for the suggestions.

No fuel shutoff.

Don't have starting fluid on hand. Any potential ill effects of using starting fluid? The mower has never needed starting fluid before.

No worries about using starting fluid for testing purposes. You can buy it from Walmart.

 

[mk378]

Some carb and brake cleaners are not flammable or barely so. Starting fluid is intended for the purpose. If you don't have any you can remove the air cleaner and drop a small amount of gasoline in the intake.

 

[cptbarkey]

Just because it ran before doesnt mean much, could still be poor gas quality. Most of the time its a carb issue with a plugged hole.
Look up your model and how to remove and clean the carb. You will only need a few hand tools and some brake cleaner or carb cleaner.

 

[TomYoung]

Summing up a number of comments above, diagnosing a no start condition on a small (or any) engine involves checking four requirements to run:1) Spark 2.)air/fuel mixture, 3) timing, 4) compression.

Always start with the easy stuff. You can check spark at the plug by removing the plug, grounding it to the motor and pull/crank the engine and watch for a strong blue/white spark across the gap (helps to be out of the sun). Fuel - squirt a medicine dropper of gasoline into the cylinder, replace plug, and crank the engine to see if it "fires". Timing - check that the flywheel key has not sheared. Compression - tough to check even with tools, but there should be some resistance to hand rope pulling, air pressure if you hold a thumb over the spark plug hole while cranking, etc..

Depending on what you find, examine the components of all four of the above systems. Spark could be on/off switch, bad wires, bad coil, bad plug, flywheel sheared, etc.. All of this can be looked up on line nowadays.

Could be wrong here, but the OP said the engine gave a couple of putts. That’s a little bit opaque, but I would take it to mean that it fired off once or twice, which probably means spark, timing or compression are okay. Beyond that, the rule with small engines is that it is always the carb. Narrow passages in the jets are easily blocked, the engines sit without running for months, even years, and the quality of fuel is never guaranteed. Gaskets leak and inline filters clog. Generally speaking, a quick burst of starting fluid can confirm this. It’s not a zebra, it’s a horse!

 

[TomYoung]

Like I said, you can learn everything typing your question into Google, etc. nowadays. I take for granted how much I was taught by mentors while growing up.

Sure, but it’s almost never the spark plug.