Dan Ferrell writes about do-it-yourself car maintenance and repair. He has certifications in automation and control technology. Engine backfires can be produced by a vacuum leak, bad timing, problems in the ignition system, a faulty sensor, an exhaust leak, or some other system fault.
Sometimes, locating the source won't take you much time, other times it can prove difficult. The backfire is produced when unburned fuel ignites inside the intake or exhaust manifold instead of a cylinder.
You can hear the combustion as a mild, cough-like ignition or a loud bang. A strong explosion, though, can cause severe damage, like cracking an exhaust manifold. Although a backfire can be the fault of a system malfunction, this malfunction may come from maintenance neglect. Have you forgotten to service one or more engine systems lately?
Start with those if you see them mentioned here. This strategy will make your diagnostic easier and your repair faster. Yes, many backfires can be prevented with a little maintenance as suggested in your car owner's manual or the vehicle repair manual.
If you don't have your repair manual yet, you should get one. Get an inexpensive Haynes aftermarket manual at Amazon for your particular vehicle make and model. These manuals include many maintenance tasks, troubleshooting strategies and repairs you can do at home. But, even if you're dealing with an intermittent backfire issue and you haven't seen the CEL coming on, scan your car's computer memory with an OBD-2 scanner like this Ancel scanner to get diagnostic trouble codes DTCs anyway. The computer may have one or more pending codes that could give you a clue about a potential system involved in the problem.
DTCs are very helpful in locating fault sources. This article will describe the causes of backfires, starting with the most common and progressing towards the more rare causes, to help you speed up your diagnostic. Any problem that upsets an ignition system spark can cause backfires and other engine performance problems. An engine needs a few thousand volts of potential for the spark to jump the gap between the center and side electrode at the tip of a spark plug.
For example, a spark plug gap may widen after the plug has been in operation for months and make it difficult for the spark to jump.Backfiring during acceleration occurs when ignition takes place in the intake or exhaust instead of the combustion chamber. The most common causes for backfiring during acceleration include an incorrect fuel-to-air ratio, a faulty ignition and bad wiring.
Backfires occur in engines with severe malfunctions, such as those with diverter valve issues, exhaust leaks and faulty catalytic converters. Backfiring caused by incorrect fuel-to-air ratios result from the engine running with either not enough fuel and too much air or too much fuel and not enough air. These issues result from a damaged fuel filter, low fuel pressure or a weak fuel pump.
Backfiring during acceleration can also be caused by internal carburetor problems, low compression, leaks in the fuel tank, lean engine conditions, and weak or broken valve springs. Backfiring caused by internal carburetor problems is a result of a defective accelerator pump. 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.
Home World View. What Is Valve Overlap?A carburetor backfire describes the small explosion that sometimes occurs when starting up a car. It generally makes a loud sound, like a gunshot, and occasionally is accompanied by a visible flame. Generally, a backfire is caused by an imbalance in the air to fuel ratio. Either the engine is not getting enough fuel, which is also called running lean, or the engine is getting too much fuel, which is also called running rich.
There are a few different issues that can create this situation. If your engine is not timed correctly, it may backfire. If your car has an ignition distributor, adjusting it may be able to correct a timing issue. Otherwise, the timing of the engine will need to be adjusted with a timing light. A faulty fuel pump, or a clogged fuel filter, is another possible cause of a backfire. Your fuel filter should be changed regularly.
A faulty fuel pump is a much bigger issue. If your fuel pump is failing, it will need to be replaced immediately. If your vehicle is equipped with a fuel injection system, make sure that it is cleaned and maintained regularly. A clogged fuel injection system will not burn fuel completely and can cause backfires. A leak in the injection system, usually the result of a stuck air intake valve, is another common source of backfires.
Using fuel injector cleaner might take care of the problem. If not, you will need to replace the faulty injector. This article was written by the It Still Works team, copy edited and fact checked through a multi-point auditing system, in efforts to ensure our readers only receive the best information.
To submit your questions or ideas, or to simply learn more about It Still Works, contact us. Why Does My Carburetor Backfire?
Fuel Pump and Fuel Filter A faulty fuel pump, or a clogged fuel filter, is another possible cause of a backfire. Fuel Injection System If your vehicle is equipped with a fuel injection system, make sure that it is cleaned and maintained regularly. Stuck Valve A leak in the injection system, usually the result of a stuck air intake valve, is another common source of backfires.
About the Author This article was written by the It Still Works team, copy edited and fact checked through a multi-point auditing system, in efforts to ensure our readers only receive the best information.Remember Me? Site Navigation. Member's Picture Albums.
I'm having a problem Identify the cause of a rather annoying and potentially dangerous problem. I was able to drive at 70MPH under normal acceleration without problems, it only occurred if i accelerated to aggressively. Anyway, any words of wisdom or helpful advice would be much appreciated. Oh yeah, its a '02 SR5 4x4 with K.
Why Does My Carburetor Backfire?
Definitely start with getting rid of those awful plugs. My money says thats the problem. Find More Posts by 4-Ripcord. Could it be a bad injector?
Im guessing that the check engine light didnt come on since you never mentioned it. SR5 Dune Silver. Supercharged 3. Camburg 2. Originally Posted by DeTwizzle. If it's breaking up under load, I'm inclined to think it's either wires or a coil.
Especially if taking the plugs in and out seems to have effected it. There's nothing visible on the coils that would show them going bad. I do think it's spark related though. Try plugs first I guess but be prepared to replace other things too.We are a group of ASE certified mechanics that have created this guide to help you save money by fixing your car yourself or to see what you are paying for when taking it in for repairs.
When your engine back-fires it can do so in one of two ways. First and the most common way is when the engine is running a small explosion of un-burnt fuel is ignited inside of the intake manifold creating a loud bang which is the backfire sound you hear. This explosion can bend the throttle actuator plate, push intake gaskets outward creating a vacuum leak and even blown apart a plastic intake manifold.
When intake manifolds were made of aluminum they could better withstand this kind of problem. This occurrence can happen once or a few times when the engine is under load. Or it can happen continuously signaling a mechanical failure which we will go over in the following repair. The second kind of problem will occur from the rear of the vehicles tail pipe which is a rich fuel mixture problem that can happen when fuel delivery parts fail such as an injector, fuel pressure regulator or intermittent ignition system failures.
A backfire condition can also occur in race cars using a turbo charger which is normal because they push the fuel through the engine which is then ignited in the exhaust system.
We will cover the primary occurrence of the engine under load first. This problem must be corrected and can not be neglected because serious engine damage can occur. On the small side of things a simple vacuum hose might get pushed off which is an easy fix. Anytime you have an engine that is backfiring the first thing to look for is a check engine light. If no warning lights are on continue down this guide. If the check engine or service engine soon light in on scan the computer for trouble codes.
This will help locate the system that is having a problem and needs repair. An intake back-fire explosion can be caused by the fuel air mixture being to lean when the engine is demanding power.
Every internal combustion engine runs on a mixture of 14 to 1 which is fourteen parts air to one part fuel. Proper fuel pressure is needed to atomize the fuel correctly when it leaves the fuel injector to complete the burn process. The most common cause for this problem is a weak fuel pump which cannot supply the volume of fuel needed for the injectors to produce a proper spray pattern or deliver the amount of fuel needed for engine acceleration.
The fuel system pressure must be tested to see if the fuel delivery system is the problem.Login to Your Account. Remember Me? Results 1 to 10 of Thread: Intake backfire on new install.
Common Engine Backfire Causes And How To Fix
Thread Tools Show Printable Version. Join Date Apr Posts Intake backfire on new install. Update Issue Fixed! Hi, I hope you can help us with the problems that we're having on this new install. It's on my Dad's car, but we're both complete novices with EFI. The Cam is a mild one, but unfortunately, I do not have the exact specs for it.
The intake is a Weiand Team G. We're running a normal distributor with no timing control, the Sniper is just connected to the coil negative. The car idles fine and if you accelerate very smoothly with a light throttle, it seems fine. Any fast opening of the throttle results in a backfire through the intake though. Even revving the engine while stationary will result in a intake backfire.
What Causes Backfiring on Acceleration?
Atomic Industries www. Register now to get rid of these ads! The H. Hey all - I'm stumped again; hemi with new small block mopar points distributer. Ran fantastic for about three weeks of hard driving, then started stumbling and breaking up until finally it wouldn't start.
After troubleshooting I replaced the condenser and car started right up. Around the block some backfiring on acceleration. Got back home and replaced the points. Gap set at. Backfiring is worse. Cleaned, checked plug gap.Why Do Cars Backfire?
All ok. Rechecked timing. Seems ok. Swapped coil - three used coils, all same backfiring on acceleration. Can start it no problem in the garage, backfires under hard revs in the garage. I'm having a hard time telling but I think it's backfiring through the carbs. If it was a small block Chevvy I'd say the cam was gone R PopeJan 25, It's new. That's what got the car running. Since you went through spark already, start by checking to see if the fuel has someway attacked the carbs fuel idle circut and is giving you a lean back-fire, maybe the pump diafram is shot?
Still more info is needed Old engine or new rebuild?? What carb s are you running?
What oil and do you run a zinc additive? Go ahead and check that the valves are all getting full lift.