Author Topic: Lawn mower help  (Read 1364 times)

tennisray

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Lawn mower help
« on: July 23, 2022, 05:46:05 PM »
My son uses a push mower to cut his grandmas yard. I can’t get it to start at the moment. Last week, I changed the blade. I turned it to the wrong side, apparently and oil was leaking out the exhaust. My neighbor helped me check the spark plug, which is working, and there is compression, but the engine won’t turn over. He thinks that we just need to give it time. But we’ve been trying to start it every day for a week with no success. Any advice?

sonofsven

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Re: Lawn mower help
« Reply #1 on: July 23, 2022, 06:46:00 PM »
Change the spark plug. Clean the air filter. Spray starter fluid into the carb with the air filter off, and try to start it.

darknight

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Re: Lawn mower help
« Reply #2 on: July 24, 2022, 04:50:34 PM »
I would recommend pulling the plug out, spray carb cleaner/starting fluid in the cylinder and pull on the starting 20-30 time to help get any oil out of the engine. Turning it over to sharpen the blade likely dumped oil into the cylinder, you just need to clean it out a little. Check your oil level too, some engines have a low oil level cutoff, if it dumped out it could be keeping it from running and you might need to add some more oil to it.

tennisray

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Re: Lawn mower help
« Reply #3 on: July 24, 2022, 07:25:28 PM »
Thank you! I had already sprayed carb cleaner and changed the air filter. Even though my neighbors spark plug tester showed my plug was working, putting a new one in solved the issue! Back working now! Thanks again!

Syonyk

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Re: Lawn mower help
« Reply #4 on: July 24, 2022, 09:30:43 PM »
A plug that sparks at ambient pressure may fail in weird ways under the compression of a cylinder.  It's not that common, but it certainly happens.  I used to have a motorcycle that would express a desire for new spark plugs by dropping a cylinder - only at wide open throttle.  Back off a hair, the cylinder would come back.  I could regap the plugs, clean them... didn't matter for long.  Bike wanted new plugs.  It was cheap, even if it did have a 3k mile plug lifetime.

You need three things for an engine to run: Fuel, spark, compression.

Compression is easy enough.  If you have a compression tester, you should see... oh, at least 100 psi, ideally somewhat more, but engines will run on less, and a small engine like that might not make 100.

Fuel: Spray starting fluid down the carburetor.  If the engine sputters for a bit and then dies, you have a fuel problem.

Spark: Usually, it either works or doesn't, but a new plug is cheap troubleshooting.

chemistk

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Re: Lawn mower help
« Reply #5 on: July 25, 2022, 06:18:40 AM »
It's also very possible that you knocked something loose in the carburetor, or knocked something that's loose into the carburetor.

Small 2 and 4 stroke engines are generally intentionally designed with loose tolerances with the expectation that owners typically won't perform routine maintenance. They will run poorly for a very long time and even when running well won't always sound that great. 

Part of that involves cheap, nearly disposable carburetors. I'd bet that spraying starting fluid directly into the intake is going to get you a few sputters and then it'll crap out. I assume that you've been using pump gas for the mower, and probably haven't been using a stabilizer to counteract the Ethanol (don't worry, most people don't).

Ethanol in pump gas can and does lead to a degradation of the hoses and seals of the fuel system. That, coupled with little pieces of dust and debris that typically live at the bottom of the fuel tank, you might have gunked it all up by tipping it on its side.

If you do get some life from the starting fluid, then you'll need to check out the carburetor. I'd look up on Youtube videos of how to remove disassemble the carb on your particular engine - the goal is to clean it up with carb cleaner and some rags, and unfortunately without knowing what kind of mower you have it's impossible to walk you through the process.

It would also be a good idea to clean out the fuel tank, and if it has an integrated filter, that too. And while you're at it, check the fuel lines - if they're tacky, spongy, or brittle they'll need to be swapped.

Spark: Usually, it either works or doesn't, but a new plug is cheap troubleshooting.

I'll second this - while you're at it, toss in another plug as extra insurance.

tennisray

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Re: Lawn mower help
« Reply #6 on: July 25, 2022, 07:43:25 AM »
Again, thank you! I’m lucky to have handy neighbors. I’m sure you’re the favorite neighbor in your respective communities, haha!

Very interesting regarding mowers not running well. We’ve noticed that a lot of our neighbors’ mowers (sputtering). But it’s a good biz model…they end up just chucking the old ones and buying new mowers every 3 years or so.

YttriumNitrate

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Re: Lawn mower help
« Reply #7 on: July 25, 2022, 08:13:07 AM »
Part of that involves cheap, nearly disposable carburetors. I'd bet that spraying starting fluid directly into the intake is going to get you a few sputters and then it'll crap out. I assume that you've been using pump gas for the mower, and probably haven't been using a stabilizer to counteract the Ethanol (don't worry, most people don't).
Ethanol in pump gas can and does lead to a degradation of the hoses and seals of the fuel system. That, coupled with little pieces of dust and debris that typically live at the bottom of the fuel tank, you might have gunked it all up by tipping it on its side.
I started using ethanol free gas for all my small engines and have noticed a decrease in engine issues. Near me, it's only about a $1 more per gallon relative to E10 or E15, so well worth it. I use this website (https://www.pure-gas.org/) to find places nearby that sell it.

chemistk

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Re: Lawn mower help
« Reply #8 on: July 25, 2022, 08:59:33 AM »
Part of that involves cheap, nearly disposable carburetors. I'd bet that spraying starting fluid directly into the intake is going to get you a few sputters and then it'll crap out. I assume that you've been using pump gas for the mower, and probably haven't been using a stabilizer to counteract the Ethanol (don't worry, most people don't).
Ethanol in pump gas can and does lead to a degradation of the hoses and seals of the fuel system. That, coupled with little pieces of dust and debris that typically live at the bottom of the fuel tank, you might have gunked it all up by tipping it on its side.
I started using ethanol free gas for all my small engines and have noticed a decrease in engine issues. Near me, it's only about a $1 more per gallon relative to E10 or E15, so well worth it. I use this website (https://www.pure-gas.org/) to find places nearby that sell it.

While that's the best option, it's not something that everyone has access to unfortunately. Personally, I keep a small bottle of fuel stabilizer and add it to the fuel jug every time I fill up.

You can even go a step further and at the end of every use season, run the small engine completely dry.

Syonyk

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Re: Lawn mower help
« Reply #9 on: July 25, 2022, 09:16:56 AM »
I started using ethanol free gas for all my small engines and have noticed a decrease in engine issues. Near me, it's only about a $1 more per gallon relative to E10 or E15, so well worth it.

Oh... yeah, I run E0 in everything except the car.

I typically get 20-25 gallons a year for "property use," which is mostly "the tractor" (though various other things use their share - the tractor works pretty hard to keep the fire break cut and to plow the driveway in the winter).  E0 premium, 1oz/gal of Seafoam, 1/2 oz/gal of Stabil.  Works fine, I don't have to fight with clogged carbs or rotting fuel lines.  I could run lower grade in the tractor, but the E0 premium works in everything, including the car (1st gen Volt needs premium, high strung little gas engine) and the motorcycles, so it's easier to have fuel I can run anywhere.

lthenderson

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Re: Lawn mower help
« Reply #10 on: July 25, 2022, 11:19:46 AM »
Oh... yeah, I run E0 in everything except the car.

I run E0 in everything including my vehicles. I used to always have problems with various oxygen sensor and other emissions faults popping up on my vehicles and finally one day, pondered that if E0 was good for small engines (which everyone seems to agree upon) why wouldn't it be better for my vehicles. I ran several tanks through my vehicles and the faults went away and haven't been back for the last 15 years or so. Anecdotal but I'm a believer. If I am somewhere where I don't have a choice to buy E0 gas, I try to just burn through the tank quickly or put a little fuel stabilizer in with it if I know it will be sitting for any length of time. But here in the midwest, most stations still have at least one selection without ethanol.

Malossi792

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Re: Lawn mower help
« Reply #11 on: July 26, 2022, 05:01:27 AM »
2 ideas come to mind:

1. About disposable carbs, yes, and no.
My mower required several carb cleaning sessions which is either time consuming or expensive. When one spring it again wouldn't start, I replaced the carb with a chinese one made for that engine, and like magic it started.
Since then, I run the carb dry when I finish mowing each and every time (so install a manual petcock).
Starts at the first pull, even in the spring after sitting half a year, using 1 year old E10.

2. If it's a 4 stroke engine, rotating the blade - and so the crankshaft backwards can screw up the timing of the camshaft, so your valves might be opening and closing at the wrong 'time' (piston position). Unfortunately if this is the case the engine has to be reassembled.

BlueMR2

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Re: Lawn mower help
« Reply #12 on: July 26, 2022, 07:46:40 AM »
Oh... yeah, I run E0 in everything except the car.

I run E0 in everything including my vehicles.

I wish we still had E0 around here.  Even at a higher cost per gallon, it might be cheaper...  My car is so old it doesn't have a knock sensor and the ECU really doesn't handle E10 properly and seems to go a bit lean.  On E0 it runs on 87 octane, but on E10 I have to spend the big $ to run 93 octane to keep the pinging under control.

Just Joe

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Re: Lawn mower help
« Reply #13 on: July 26, 2022, 12:20:37 PM »
Be careful rotating that blade around without the spark plug disconnected - this could start the lawnmower. Unlikely b/c it is having starting problems but why risk it?

Always disconnect the spark plug when messing with the blade.

Timing can go out of spec if you hit a rock or root with the blade. Some lawn mower engines have aluminum flywheel keys meant to shear in a blade collision to protect the crankshaft and help keep it from breaking. To repair you just remove the flywheel nut on top of the engine, extract the old key and drop in a new one. You might need to remove the flywheel to pick out any old pieces of crankshaft key.

 

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