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Backfire in engines is caused by simple chemical malfunctions that can be easily rectified. A backfire in a lawnmower engine can damage both the engine and the exhaust as burning fuel explodes. Take care to avoid close proximity to a backfire and the motor until you've determined the cause and fixed the problem.


4: Backfires in Exhaust Note: It is normal for many high performance exhaust systems to moderately backfire or pop when the throttle is closed from mid-to-high rpm. In fact, one should expect a well-tuned high performance engine to "pop" and "crackle" when the throttle is closed at high rpm.


When you hear a backfire, you need to determine whether it is backfiring out the exhaust or back up through the carb. We usually refer to an exhaust backfire as a "backfire", and backfiring through the carb as "spitting" or "coughing". "Backfiring" is usually caused by a spark plug "sparking" when it isn't its turn and the exhaust valve is open...


Also I ran the engine with the lines off of the airpump diverter and I have exhaust coming through the pipes. So I’m going to guess that both check valves and diverters are bad Does that sound right? My 74 had the same issue but with headers and tuned up it doesn’t backfire in the exhaust anymore.


What causes an exhaust backfire when you let off the pedal....the crakling and so on.... reson is that i have a 355 with sportsman II's and XE268 i will be running Hedman 1 5/8 primary headers to a 3" collector I want to run a dual 3" system with and X-pipe, flowmaster 40's and turndowns at the...


backfire is a result of half burned, hot exhaust finding oxygen to finish burning. I'd change the spark plug first. I'm guessing its also hard to start or does it just do this when the engine has been running? - Craftsman Riding Mower


An engine backfire is an explosion produced by an internal combustion engine. A backfire results in a temporary loss of power and forward motion along with a loud popping noise. In some cases, a backfire may cause a burst or flame to shoot from the vehicle’s exhaust.


What causes a 1973 Pontiac 350 engine to backfire through the exhaust? A large backfire is most likely caused by a bad spark plug or plug wire. Unburned air and fuel pumped into the exhaust will ...


Model 858F8A, the motor is backfiring and stopping the engine dead every five or ten seconds. The backfire is coming out the exhaust, not the carbs. Checked spark on all three with spark checker, all are firing strongly. Pulled wire from each plug one by one, grounded that coil wire to the spark tester, and ran.


Briggs and stratton then replaced the engine after two years of fighting with them and more than $1000.00 spent on their part. The new engine has only 5 hours on it and is now backfiring thru the exhaust, but has not spewed gas out of the carb as of yet. Contact the U.S. Consumer Protection Commission in Washington and report this to them.