Briggs & Stratton
Engine starts and runs fine except that it backfires thru the exhaust.
Experienced gardeners share their insights in answering this question :
This is a true tale sign of a valve being out of adjustment or possible burnt or sticking. Most likely its just out of adjustment. Setting them to Book Specifications of: Valve Clearance (cold) IN and EX .005″ (0.13 mm) should take care of the problem. Since you said that it runs fine rules out the possibility of a sheared flywheel key, though I have seen one run with it slightly sheared. Thanks; George
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Gasoline that contains alcohol has a tendency to ignite easier, which can cause afterfire. Small engine muffler type and manufacture. Carburetor adjustment may not be properly set for correct engine performance. Anti-afterfire solenoid may not be working properly.
The spark inside the chamber may not burn up all the fuel, allowing a little extra gasoline vapor to enter the exhaust, and lead to a backfire. This can be caused by a faulty mass airflow sensor or a clogged engine air filter “choking” the engine and not allowing enough oxygen to flow into it.
Backfire, or more accurately “after fire” when it occurs when stopping an engine, is caused by unburned fuel/air mixture being ignited by the heat of the muffler.
If you were to be dumping too much fuel through a carburetor into your engine,” says Louwerens, “then what happens is you`ve got too much fuel, it didn`t burn it all, then it ends up igniting at the wrong time, and then you get that backfire effect.”
On the other end of the spectrum, a bad fuel pump, vacuum leak, or clogged fuel injectors could cause an air-fuel ratio that`s too lean; that is, it has too much air and not enough fuel. Though this is the opposite problem, it can also cause a backfire as vapor escapes into the exhaust and combusts there.
Another possible cause of your backfire is a spark plug refusing to “spark” when the exhaust valve opens. If the air/fuel mixture has become too rich, unburned fuel is left in the exhaust system. The misfired spark plug ignites the rich air/fuel mixture, causing a loud “bang” in the tail pipe.
If your engine is getting more fuel than it needs, a rich fuel to air ratio is the result. When your car has leftover fuel in the exhaust and the cylinders, that fuel explosively burns and creates a loud popping sound. Specifically, here we mean delayed timing, which causes the backfire.
Assuming all of your plugs and wires are in the correct locations and you haven`t messed with the timing at all, then the most common cause of backfiring through the carb (spitting or coughing) is in the morning when a carb`s air/fuel mixture is a bit too lean. This usually goes away once the engine warms-up.
An Afterfire occurs only after the engine has been shut down. A Backfire can occur at any time.
Another possible cause of your backfire is a spark plug refusing to “spark” when the exhaust valve opens. If the air/fuel mixture has become too rich, unburned fuel is left in the exhaust system. The misfired spark plug ignites the rich air/fuel mixture, causing a loud “bang” in the tail pipe.
One of the most common causes of a sputtering engine is an issue with the vehicle`s fuel system—the filter, pump, and injectors. These three critical components work together to ensure fuel flows smoothly from the fuel tank to your engine`s fuel injectors, and then pumps into the engine evenly.
Discover Relevant Questions and Answers for Your Specific Issue
the most relevant questions and answers related to your specific issue
How do I remove and clean air filter? – Briggs & Stratton Lawn-Boy 10640 20-Inch 6.5 HP Gas Powered Lawn Mower
ANSWER : There should be a square of plastic on the side of the engine which is opposite of the muffler. It has a small hex head with a slot cut in it. Remove this plastic cover and the air cleaner should be inside of it.
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<!– from fixya rte –>Backfire, and will not restart – Briggs & Stratton Briggs Stratton Lawnmower Lawn Mower Short Block
ANSWER : 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
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Backfires and will not start – Parks Optical 13.5hp Briggs And Stratton Intek Lawn Mower Engine
ANSWER : Be more specific make sure your motor has an exhaust the motor should be sucking in fuel and you might want to rev the motor as soon as you start it
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How many cycles is a 6.25 hp Briggs & Stratton engine ?
ANSWER : 4 cycle.
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Wshat is the valve clearence for a 24 hp briggs and stratton engine model 446677 type 0470E1 code 050405yh
ANSWER : About a mm or .004″.
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I see no vent holes om my 675 series briggs and stratton engine fuel cap
ANSWER : There are holes in it should be three or four. a rubber diaphram is covering it but they are there
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Riding mower keeps back firing and will not start
ANSWER : You have a sheared timing key it is under thefly wheel replace says the red neck
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My Briggs & Stratton gives off a puff of blue smoke when I first start it. When in idle it will REV up & down and give an ocassional backfire.
ANSWER : Sounds like you may have too much oil in the engine. Check your oil level.
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