Experienced gardeners share their insights in answering this question :
Is it a push mower? Just curious…
Generally when this happens, the spark is firing out of time. What did this is probably a hard object was hit with the mower and the flywheel key was sheared or offset in shear. They are pretty soft and designed to take the brunt of such a hit to the engine.
Anyway, if this is the case, remove the flywheel and put in a new flywheel key.
Crank her up…
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.
The primary cause of a backfire is decelerating too quickly. The simple fix for this is just to lower the engine speed a bit more gradually. If you have a throttle that you use to reduce speed, gradually let it up instead of letting it rebound quickly.
Answer: Bad plug wires (jumping spark) and a bad distributor cap are common to both misses and backfires. Other things you might want to check: vacuum leak, bad fuel injectors, and the carburetor accelerator pump.
If your lawn mower begins to backfire and does not start, it is most likely due to a faulty fuel system. It`s possible that the gas is old and has gone bad, or that there is water in the tank. In either case, you`ll need to drain and replace the fuel in the gas tank.
Backfires and afterfires are worth paying attention to since they can cause engine damage, power loss, and decreased fuel efficiency.
An engine backfire occurs whenever the air-fuel mixture in your car combusts somewhere outside the engine`s cylinders. This can cause damage to your car`s exhaust or intake if left unchecked — and it also means that your car`s engine isn`t making as much power as it should, and is wasting lots of fuel.
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.
The main difference between a misfire and a backfire is that a misfire occurs when an engine`s cylinder fails to fire (incomplete combustion) whereas a backfire occurs when complete combustion takes place outside the cylinders.
A dirty or fouled spark plug can cause your lawn mower to not start. It can also work itself loose, causing issues. If the spark plug appears to be seated correctly but the engine doesn`t start, a new one may be in order. For a few dollars, this easy fix can get your small engine working again.
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.
Discover Relevant Questions and Answers for Your Specific Issue
the most relevant questions and answers related to your specific issue
The lawnmower won t start after pulling the start up cord . changed the spark plug it still won t start
Try a touch of starting fluid right into the carburator by taking the air filter off. If it then starts but wont run or stay running, the reservoir below the carb should be removed to clean at and the pinhole in the intake tube above the bowl nut. This is the most common problem with lawnmower start problems, the pinhole can be unplugged with one wire from a wire brush. Be careful with the gas, at least pinch off the gas hose with a vise grips while removing the carb bowl.. Never use a droplight around gasoline.
Ride on lawnmower lr35 just clicking and wont start
Check battery and starter cables for tightness and corrosion. also battery voltage.
<!– from fixya rte –>Backfire, and will not restart – Briggs & Stratton Briggs Stratton Lawnmower Lawn Mower Short Block
Lost valve seat my have to short block engine take in for valve job but be prepared if thet say your need a short block valve job 150 .00 to 200.00 short block 600.00 tp 800.00 dallars
MOWER USES A LOT OF GAS BACKFIRES SOMETIMES& TRIES TO STOP BUT PICKS BACK UP
Sounds like the carb needs to be rebuilt
My lt1000 turns over and while turning over backfires. does not start. Started backfiring a couple weeks ago while in operation. would backfire, engine would die, wait a few and started again. finally, just backfires while turning over.
The engine should be an OHV type. You could try adjusting the valves under the OHV cover. Kinda like the valve lash on cars. When the valves are at rest you can set each one to about .004 with a feeler guage. You can look on youtube for a video one adjusting lawnmower engine valves. Seeing it is easier to understand then reading it.I hope that this helps you get it fixed.
Help with the lawnmower. It starts and stalls after a few seconds
Check the fuel system clean the carb .
How to take off carbarator – Briggs & Stratton Briggs Stratton Lawnmower Lawn Mower Short Block
Usually there are two screws. On some newer mowers the same screws hold on the Air Cleaner housing.
Lawnmower starts and dies… where is the main jet for the carb?
cleaning the air filter, then a touch of starting fluid right into the carburator by taking the air
filter off. If it then starts but wont run or stay running, the
reservoir below the carb should be removed to clean at and the pinhole
in the intake tube above the bowl nut. This is the most common problem
with lawnmower start problems, the pinhole can be unplugged with one
wire from a wire brush. Be careful with the gas, at least pinch off the
gas hose with a vise grips while removing the carb bowl.. Never use a
droplight around gasoline. most lawnmowers have no mixture adjustments, so it is a matter of cleaning the carb, tank, gas lines. Some oils in gas mix systems settle and clog after less than one season.