it idles it seems to be fine.I replaced the fuel filter and cleaned the plugs and filter. Any ideas before I start digging into it.
Craftsman

Experienced gardeners share their insights in answering this question :
I would check the exhaust and intake valves clearance. The exhaust valve may be leaking and sometimes improper valve clearance will cause this. Also a dirty carb can cause it to run to lean at high speed and make it do this sometimes.

How to Identify and Fix Common Gardening Problems ?

We provide a variety of viewpoints on how to identify and fix common gardening problems. Our sources include academic articles, blog posts, and personal essays from experienced gardeners :

Low fuel pressure can cause a backfire when there`s too much air and not enough fuel in the combustion chamber. This can be rectified on lawn mowers with speed settings by simply increasing the speed and thus increasing the fuel supply. Another possible cause is a failing fuel pump or even an old fuel filter.
Clogged or Dirty Air Filters

Dirty air filters are one of the most common reasons lawn mowers sputter. Dirt can be present in the apertures that lead from the carburetor and the fuel filter and interrupt the flow of fuel supply to the combustion chamber. You want to be sure to clean or replace dirty air filters.

A clogged carburetor is most commonly caused by leaving fuel in the lawn mower for a long period of time. Over time, some of the ingredients in the fuel may evaporate, leaving behind a thicker, stickier substance. This sticky fuel can clog up the carburetor and cause the engine to stall.
When an engine is running rich, it has too much fuel and too little air, which slows down the combustion process. When combustion doesn`t happen in a timely manner, the exhaust valve opens while the air-fuel mixture is still igniting, causing this explosion to “spill” out of the cylinder, making a loud popping noise.
Loose, Dirty or Disconnected Spark Plug in Your Lawn Mower: Check it out, clean off debris, re-connect and tighten. Dirty Air Filter: Clean or replace. Fuel Not Reaching the Engine: Tap the side of the carburetor to help the flow of gas. If this doesn`t work, you might need a new fuel filter.
If too much fuel is added to the engine, it may not all burn up before the exhaust valves open — letting unburned gasoline into the red-hot exhaust headers, where it can combust and lead to a backfire. Too much fuel could be getting into your engine due to damaged and leaking fuel injectors or bad engine sensors.
Excessively lean carburetor settings can contribute to backfiring. If the mixture is too lean, it may burn very slowly and unevenly. This condition, in turn, may result in burning mixture remaining in the cylinder until the beginning of the next intake stroke when it can ignite the incomming air/fuel mixture.
A clogged fuel or air filter can make your engine sputter and your acceleration lag because the engine is not getting enough fuel or air, respectively. The combustion chamber needs the correct amount of air and fuel in order to generate combustion efficiently.
If your lawnmower is starting and then stalling, the most likely issue is the carburetor. The most common issue is that the carburetor is dirty. Here`s what you need to know about how a dirty carburetor can cause a lawnmower to start, then stall out and die.
If your lawn mower starts, runs for a while, then dies, check the ignition coil, gas cap, and spark plug. One or more of these parts could be causing your problem. Follow our repair and symptom guide to help you fix this.
Are These Sounds Serious? Most of the time, car popping sounds are nothing to worry about. However, if you think you may have an engine knock, it`s important to have your car checked out by a mechanic as soon as possible. Engine knock can damage your engine if left unchecked.
Block off the fresh air injection systems. This will reduce the air being fed into the exhaust, causing the higher exhaust temperatures and detonation. 2. Adjustment to the fuel table in the zero percent fuel column from 2,000 rpm to redline, may also be needed to help reduce popping.
This sound is the result of friction from the gear teeth meshing inside the transaxle casing. These gears will wear slightly over time, and this sound should decrease. If the noise suddenly becomes louder, we suggest that an authorized service center inspect the unit.
A full gas tank and oil reservoir are the essential first steps when checking why the lawn mower won`t stay running, but the problem could also be a dirty filter, clogged carburetor, improper fuel mixture, or a dirty spark plug.
A clogged carburetor is most commonly caused by leaving fuel in the lawn mower for a long period of time. Over time, some of the ingredients in the fuel may evaporate, leaving behind a thicker, stickier substance. This sticky fuel can clog up the carburetor and cause the engine to stall.
Has your car been backfiring? It can often sound like a gunshot, if not a “cough” or a “sputter”. While an engine backfire (or “afterfire”, if it occurs when the engine has already been shut off) will not harm your vehicle, it can be inconvenient and interrupt any peaceful drive.
Engine Backfires

Backfiring can damage other parts of your car if it`s allowed to continue, so it should always be checked out. But it`s sometimes caused by the ignition coil failing to ignite the fuel in the combustion cycle, and allowing it to infiltrate the exhaust system.

If your riding mower`s e engine runs rough or misfires, the carburetor could be clogged.. Rebuild or replace the carburetor if it`s clogged. If the engine runs rough after hitting a rock or stump, check the flywheel key-a damaged flywheel key will disrupt the ignition timing.
Common signs include reduced engine performance, black smoke coming from the exhaust, backfiring, overheating, or hard starting.
A sputtering engine may just mean you need to have your fuel filter replaced. All vehicles have a series of vacuum hoses that create the fuel pressure. If one of them leaks or is damaged in any way, you will lose significant fuel pressure. The vehicle`s exhaust system can greatly impact the engine`s performance.
Low engine oil can cause a misfire, and it is very likely that the cause of the misfire was indeed the low oil pressure in your vehicle. There are three common ways low oil can cause a misfire: Your oil filter is damaged, reducing oil flow, causing improper valve timing, and resulting in a misfire.
Your lawn mower runs for 30 minutes then dies if you are having issues such as a bad spark plug, air problems, a malfunctioning carburetor, or a faulty gas cap. You may even encounter the issue that your lawn mower runs for 5 minutes then dies.
Condensation inside the gas tank is one culprit, but moisture can also enter the system through a loose or ill fitting gas cap. The best solution is to drain the mower`s gas tank and refill it with fresh gasoline. A clogged fuel filter can also cause a mower engine to die.
An engine that will fire and run with the choke closed but dies when the choke is opened likely has debris at least partially blocking the fuel passages in the carburetor. In this condition the closed choke provides enough extra fuel to enter the engine to overcome the lack of fuel flowing through the other passages.

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My toro 6.5 hp push mower (2010), has no fire to the plug. I have not abused it. i have a small yard and it just gets normal use. Now it won’t fire. I first changed the fuel and cleaned the carb thinking it was that crappy ethanol again. but i grounded out the spark plug and cranked it…no spark. I think it has to do with the lever you pull back to start it . they have some stupid complicated safety contraption that rides along the fly wheel when you pull back on the handle for starting and shutting off the engine. …it looks worn out already…like a mini brake pad. any ideas?…do i really have to replace this garbage every year or am i on the wrong path here?
ANSWER : Unhook your wire from the coil that goes to shut off mechanism, and see if you have spark then. the wire may be grounded out, or your coil might have took a ****

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Wont start no ignition put new plug in and fuel filter
ANSWER : Flush gas tank, fill with fresh gas and Stabil. Replace air filter. Remove bowl from carb clean bowl and holes in bowl screw.

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I have a Poulan push mower that after mowing in a ditch started making a loud noise and running rough. It almost sounded as if metal was hitting metal. The mower was vibrating more than normal. I checked under the mower and nothing is hitting. After a few times of stopping the mower engine because it sound as if it is going to die down the mower will not start now. The shaft does not appear bent and the blade appears ok. The mower has oil, a good spark plug and a clean air filter. It was running fine until that moment. I did not see anything that I hit but it is possible I hit something in the ditch like a pine cone or branch. What could the problem be and how would I go about fixing it?
ANSWER : If you are sure the oil level is correct then it sounds like it’s about to die, unfortunately. A pine cone shouldn’t cause any damage, but a large branch may do so. Was it smoking before you shut it down? The vibration could be caused from a bent blade. It could also be caused from a part breaking in the motor. I wish I could have given you better news!

Good Luck,

Jim

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I have had a poulan pro 550 series push mower for almost 1 year at the end of the season last year the mower would start briefly and then stop. i have cleaned out the air filter and that did not help.the mower started, i made one revolution around the yard 3/4th of the way the mower quit. I then primed the mower it started then quit and now it will not start at all. Does anyone have any suggestions of what to do. Thanks
ANSWER : There is a little spring that works the carburetor arm. If that popped off then the mower will not run.

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<!– from fixya rte –>Rj19lm plug gap for a 195cc 4cyl lawnboy – Lawn-Boy lawnboy" Mower Blade 21"
ANSWER : As a starting point in my shop i always use 0.30 in. For all my mowers

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Have a craftsman 16″ chain saw 358.360260. Could not initially get it started after it had sat for a couple years with fuel stabilizer in it. When I went to use it the fuel had all evaporated and the fuel pick line was rotted. I replaced that with some difficulty but finally got it on. Saw still wouldn’t start. Replaced the fuel filter. Still wouldn’t start. Pulled the carb apart and cleaned and recleaned everything. Diaphragms were good and I didn’t adjust any of the mixture screws because as I said it ran fine before storage. Non of the carb passages were clogged. Fresh gas 40:1, good spark plug and good spark. Airfilter is good. Engine has maybe about 4 hours of total run time on it. It’s a ZAMA (?) carb. It will run for about 30 seconds when I manually prime it by pouring a small amount of fuel directly though the carb. When I was disassembling the carb the vent hose that goes back into the fuel tank seemed to have a small out of ?substance? in it which I cleaned out. It was right at the end the of the hose that goes back into the fuel tank and not up by the carb. It didn’t appear to be like your typical gummy deposits/varnish though. I hope it wasn?t some type of spongy check valve stuff that is supposed to be in there. That might explain some of my problems. Anyway, I also can not seem to get the primer bulb to fill. When I open the fuel tank, look in side and depress the primer bulb, air bubbles come out of the fuel filter. But when I let the bulb reexpand there’s no fuel that gets sucked up the hose. I can however seem to fill the primer bulb when the fuel tank is full and the chainsaw is laying on it?s pull cord side and the bulb is depressed a bunch of times. The saw will also start and run again for about 15 seconds then die. It’s definitely not getting/fuel and probably running out . Thanks.
ANSWER :

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Lawn mower will start and run for 5 seconds and shut down
ANSWER : Will it stay running with your choke on? if so then clean your carb. if not then look for a blockage from tank to carb. ie fuel shut off, deteriorated fuel line. plugged filter etc

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Chainsaw stalls Chainsaw is 4 years old and has a history of moderate use. After I ran the saw about 1 minute on plain gas (grabbed the wrong gas can – ouch) the chainsaw sputtered and stopped.

It didn't seize, and the pull starter never became more or less difficult than normal. The engine would continue to start if I pressed the prime bulb and engaging the choke, but stall again after 10-20 seconds. The temperature that day was about 50 degrees F and I was running the saw with the “cold plug” installed (per warm weather running).

When it refused to keep running I did the following:
Flushed the fuel tank (that's when I saw the gas had no oil in it).
Ran hardware wire through all of the fuel lines.
Replaced the fuel filter and spark plug.
Cleaned the air filter with a nylon brush and compressed air.

Same behavior (start then stall in less than 20 seconds). I made at least 20+ attempts to start it.

I removed the carburetor and, though it looked perfectly clean, I took off the top and bottom covers then sprayed everything with automotive carb cleaner and blew out the passages with compressed air. The gasket and diaphragm looked new. No pinholes in the diaphragm when held against a bright light. I reinstalled the carb but got the same behavior (start then stall in less than 20 seconds). I again made at least 20+ attempts to start it.

I disassembled the short block and saw that the piston has some slight scoring on it. The ring is clean and I verified that the piston ring has .001 clearance between it and the piston ring groove all the way around with the ring held tightly in place (I was thinking that the piston might have become deformed if it did indeed get too hot when run without any oil premix).

The cylinder wall has no scoring and there isn't any signs of melted aluminum anywhere. The crank is clean as was the inside of the crank cover.

I reinstalled the crank cover using permatex non-hardening gasket goop and torqued the cover bolts to 10 inch pounds. I reassembled everything else per the exploded diagrams in Echo's “parts manual” for the CS400.

During assembly I took note that both the carb gasket and intake boot look like new.

Still the same result: press prime bulb once, engage choke, pull a few times and it starts but stalls after 10-20 seconds.

I'm stumped.

ANSWER : Not sure what to say other than its fuel starvation, if not already done replace the fuel filter in the tank, if no better i would suspect a massive air leak, so replace the crank seals, if there is no primary compression in the crankcsae fuel will not pull through the engine, good luck.

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