A lawn mower is an extremely useful garden tool in keeping the yard neat and beautiful. However, it needs a bit of maintenance to avoid potential problems during its operation such as stalling and backfiring. Even a riding lawn mower is subject to these operational issues although it is more powerful than hand mowers.
A backfire could be quite a scare for the lawn mower rider and all those around it as it sparks off a surprisingly loud noise that could catch everyone off their guard. It could happen at any time like when the yard work is almost done and the lawn mower is being shut off for the day. The loud noise could spring a shock to the mower rider when the fuel is set off in the muffler outside the engine. Although the backfire does not hurt the engine in any way, it is a clear symptom of a potential problem in the machine.
Troy-Bilt 420cc OHV 30-Inch Premium Neighborhood Riding Lawn Mower
Table of Contents
Reasons for Backfires
The backfiring of the mower could happen right after the mower engine is shut down. This could be caused by incorrect settings on the carburetor or problems with the muffler construction. Hence, these components of the mower machine must be checked as quickly as possible to rectify the issue and avoid greater problems arising.
A backfiring could also happen from the wrong type of gasoline injected into the lawn mower. Poor quality gas poured into the lawn mower could create a backfiring of the mower as such gas tends to ignite its alcohol content in the muffler instead of the engine like other non-alcohol gas. Hence, mower owners should consider using only low-alcohol gas, if not non-alcohol option, to resolve the issue.
Another occasion for such a mower backfire is during the idle time of the lawn mower or when the engine is being turned off too quickly. When the engine speed is slowed down too quickly, a backfire could happen as the mower has been in active mode with a rapid movement during mowing operation. Its engine speed has been on the high to be turned down quickly; the sudden speed change causes the gas to be pumped into the muffler that causes the gas to ignite.
Lawn mower users need to reduce the engine speed gradually to allow the engine motor a gradual shutdown. The motor should be left idle for about 15 seconds before it is turned off completely to reduce backfire potentials.
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A mower backfire could also backfire if the mower is overheated. The hot engine may heat up the gas to be pushed to the muffler or it could be a lack of air flowing to the engine. Lawn mower owners should contact the machine supplier or manufacturer on enhancing the air flow to the engine to prevent backfires.
Safeguard Components
Starting up a lawn mower should not generate any backfire but if it does happen, it is a clear indication of damage on the mower. Mower owners may need to reflect if the mower had run over some huge obstacle during its operation that could have damaged some components to cause the backfiring. Mowers owners could install safeguards to enable less costly components such as flywheels to be broken or damage instead of the blade which is a most expensive mower component.
Hence, the blade is kept safe at the expense of less costly components which could be easily replaced without feeling the pinch. This is highly advisable when there are many stones or rocks in the yard and mower users do not have time to clear the yard of these potentially dangerous obstructions prior to mowing.
The blade and the crankshaft are the most expensive mower components which should be protected as much as possible to enjoy greater savings. A broken flywheel would probably cause the mower to backfire or stutter when the mower is switched on but do not engage completely for a full functionality. This may cause the mower to be inoperable unless the flywheel is repaired or replaced. However, if the backfiring occurs during a mower start up, it is best to consult professional mower repair services before restarting the mower to be safe.
Various lawn mowers may come with specific components whose function is to prevent backfires even after the engine is turned off. These safeguard components are known as anti-after fire solenoids which allow the engine to be turned off at any speed without a gradual slowing down. Hence, there is no problem of excessive fuel rushing into the muffler to create a backfire.
However, such troubleshooting of the lawn mower and the replacement of safeguard components such as the anti-after fire solenoids could prove challenging to an ordinary mower user unless it is a DIY enthusiast on lawn mowers. It is best to call the professional service provider on lawn mowers especially a specialist of that particular mower brand or company. Professional mower experts are usually licensed professionals with apt training on mower repairs with adequate repair facilities and tools to correct the situation safely.
Difference between Backfire and Afterfire
A lawn mower could experience either a backfire or an afterfire. The former refers to the condition of a loud bang or explosion sound during a mower engine shut down. The latter refers to the loud noise after the engine is shut off.
Mower owners need not be overly concerned about backfiring or after firing through the carburetor as the engine is not affected adversely. However, it is advisable to identify its cause especially if it occurs rather frequently. Backfiring and after firing are indications of potential problems with the mower which should be resolved as quickly as possible before major repairs happen due to major damages on primary mower components.
A backfire brings about a loud bang or boom when the mower engine is rapidly shut down or the rider rises up too quickly from the seat to trigger the safety switch. A backfiring could also bring on degradation of engine power which might trigger off other issues. This would require professional troubleshooting skills to identify the actual cause of the problem before implementing the best of solutions to resolve the issue.
Causes of Backfire
1) Shutting down of the engine too fast
2) Inappropriate injection of poor quality or stale gasoline with higher alcohol volumes
3) Poor adjustment of carburetor
4) Poor muffler construction
5) Overheated engines
6) Highly sensitive carburetors on transitional air flow passage
Possible Rectification Solutions
1) Reduce engine speed slowly until full shutdown
2) Abide by the engine fuel recommendation
3) Use non-alcoholic gas as engine fuel
4) Adjust carburetor to enjoy optimum performance
5) Increase air volume for better air flow to lower engine temperature
Causes of Afterfire
1) Rapid engine shutdown causes the fuel to pump quickly to the engine
2) Gas with alcohol content causes quick ignition
3) Small engine muffler
4) Improper setting of the carburetor
5) Malfunctioning anti-afterfire solenoid
Possible Rectification Solutions
1) Cool the engine for at least 15 seconds by letting it be idle before shutdown
2) Use non-alcohol gas fuel
3) Check on proper carburetor settings that encourage optimal performance of the engine
4) Replace parts with updated components
5) Check condition of anti-afterfire solenoid regularly
Factors of Consideration
Lawn mower owners who wish to avoid backfire or afterfire should consider some factors at play. This would involve alcohol-content gas used as mower fuel. It is found that riding lawn mowers may not be properly designed to burn such fuel safely which results in occasional bouts of backfires as well as power loss in the mower.
It is best that lawn mower owners should use pure gas or fuel along this line to avoid backfires. Water-contaminated fuel could be another cause of mower backfire and power loss. This could be resolved by emptying the gas tank of the fuel to be dried before putting in fresh fuel to fire up the mower.
A lean carburetor could also be the cause of backfire when it has too little fuel in the gas and air mixture. A backfire could also occur if the carburetor has too much air in the mixture. It is the carburetor which regulates the air and gas volume requirements for proper and complete combustion. A good balance is essential for an optimal combustion and functionality as too little or too much could bring on backfires.
A damaged or worn-out spark plug could also cause backfires as there is an improper gap between the electrodes. A weak spark generated is not strong enough to ignite the motor but backfires in the heated exhaust muffler.
Conclusion
So there are many causes for lawn mower engine backfiring while starting. Once you know the exact reason, you would be easily able to take the corrective action.