Why Does a Car Slow Down, Sputter and Then Backfire on Acceleration?

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Superior Car Talk explains that a sputtering and backfiring problem is usually the result of moisture condensation in the fuel system. While the fuel tank may be tightly capped, water can still seep in over time as the result of temperature extremes.

According to Superior Car Talk, many people drive with their tanks half full. As a result, changes in the humidity and outside temperatures can result in an accumulation of moisture in the tank. Every time the gas pedal is pressed or a driver accelerates, water seeps to the bottom of the tank and into the fuel system.

While the fuel filter removes a certain amount of moisture, an older filter may cause water to flow into the engine, thereby causing backfiring or sputtering. Superior Car Talk recommends changing the filter every approximately every six months to prevent a sputtering or backfiring problem.

If changing the filter does not alleviate a sputtering or backfiring issue, the site advises car owners to visit a mechanic to check the wiring or to clean out the fuel tank. The site adds that any problems with banging or popping sounds should be addressed immediately because waiting to see a mechanic can result in engine damage.