"Backfiring" is usually caused by a spark plug "sparking" when it isn't its turn and the exhaust valve is open. If your air/fuel mixture is too rich, and you have unburned fuel in the exhaust system; cross firing from one spark plug wire to another can occur. If they are touching each other and when this happens while the exhaust valve is open, it will ignite the rich / unburned mixture in the exhaust manifold and tail pipes and result in a big bang. Back firing can also be cause by a cracked distributor cap, or one that has carbon tracking inside which causes cross firing between the terminals inside, which in turn, sends spark to a spark plug that isn't ready for it yet.
I, too, would like to know the answer! I have a 1993 Polaris Trail Boss ATV with the 250 cc engine... it tends to backfire when letting off the throttle.
Out of time.
Too much PSI.
Backfire is normally caused by engine out of time, or spark plug wires installed incorrectly.
There are many causes to this problem, in a 1999 Ford Ranger 3.0L. It is usually caused by a spark plug firing when its not suppose to, or late/delayed timing.
As with any engine, timing, and also carb problems.
It's lean. You have to figure out why.
If your engine backfires when trying to start and the valve timing is correct, then it could be electronic ignition unit or the pick up that causes the spark to occur with wrong timing.
Timing is off. You may need a new timing belt.
Several issues can cause a back fire:OverheatingLean mixtureFaulty ignition
Unburned fuel in the exhaust system causes the backfire from the exhaust pipe.
That usually means the engine is lean. Could be a vacuum leak.