Generator Making Popping Sound When Starting

In this blog, I will be explaining to you the issues and problems while starting a generator that will answer the questions why is your generator making a popping sound when starting? So, if you have an issue with your generator while starting and it’s making a freaking noise. You are at the right place to get the answers to those issues.

I will explain in detail the issue and solution. So, let’s get started!

A generator should not normally make pop sounds. Something is also amiss if you see a strong smoke coming from the exhaust or carburettor. Most individuals automatically assume that they are symptoms of a backfire. They are, in some way, correct. However, there is a distinction to be made between a backfire and an after fire. The carburettor emits a pop sound or smoke when the former is used. The latter occurs when the exhaust emits smoke or makes a popping sound. So, what’s the source of these problems?

Generator Making Popping Sound When Starting

If your generator pops when running normally, it suggests there is a problem with the combustion system. A poor air-fuel combination is frequently the cause of the pop sound. It’s also possible that some of the combustion system’s components are broken.

Popping isn’t always a major issue. However, you should not dismiss it because it could exacerbate a major problem. The best course of action is to have a mechanic examine the various sources of pop. Because most popular difficulties deal with oil combustion, it should be straightforward to spot.

Material Needed
Air Fuel Ratio Gauge

Popping sound occurs when the generator carburettor is challenged. Your generator can backfire due to a single issue or a mix of issues. The following are the most common reasons for the problem:

  • A carburettor with a restricted combination of air and gasoline
  • Fuel combustion begins early.
  • There’s a problem with the intake valve.

A Carburetor with a Restricted Combination of Air and Gasoline

An adequate supply of oxygen to the fuel is required for efficient combustion. The rate of fuel combustion will be slow if the supply of air is insufficient. Even when the supply is slow, you’ll see that there is still fuel combustion. However, because the pace is so sluggish, it will take longer than usual to burn a unit of fuel.

As a result, combustion will continue even after the power stroke is completed. As a result, when the generator’s piston rises during the exhaust stroke, the combustion process will be interrupted.

Two things happen in this step that causes the generator to malfunction.

During the exhaust stroke, the exhaust valve opens first, which is what you should expect. The intake valve then opens, allowing new air and fuel into the combustion chamber.

It’s worth noting that the preceding air and fuel mixture is still being burned at this point. The slowly burning fuel’s flame will ignite the new entering mixture, resulting in a loud pop sound. It can also be coupled with a flame, which will result in a backfire.

The first step in dealing with such a problem is to inspect the air jets. Likely, they’re not allowing enough air into the combustion chambers.

Fuel Combustion Begin Early

During the intake stroke, the piston usually presses downwards to let the air-fuel mixture enter the combustion chamber. The piston begins to rise once enough air and fuel have been introduced. The intake valve should be closed during this time.

However, the valve does not always close on time. There will be burning of the air-fuel mixture on the combustion plug if this happens and the spark plug produces a spark. The piston will carry the burning air and gasoline to the carburettor, generating a backfire.

The timing error can be caused by a variety of factors. It’s possible that the ignition coil is faulty and ignites at the incorrect moment, that the spark plug is damaged, or that the flywheel key is malfunctioning.

There Is A Problem with Intake Wall

For the fuel combustion system to function properly, an intake valve is required. It opens and closes methodically to allow the air-fuel mixture to enter the combustion chambers. Expect the carburettor to backfire if it opens when it should be closed.

A malfunctioning inlet valve can be caused by several factors. First, the system’s rocker arm may be malfunctioning. In addition, the synchronisation of the pushrod system and the valve may be faulty. It can also happen if the valve is rusted or worn out due to wear and strain.

The intake valve will open when it should be closed in either of these situations. As a result, it will enable gasoline to flow when it is not supposed to. After that, the air-fuel mixture returns to the carburettor. As a result, it is one of the primary causes of generator backfiring.

To diagnose the problem, remove the lid and check that the rocker arm is in good working order. You should also double-check the location of the springs. They should be squeezed into the ideal situation. As a result, if they aren’t, there’s an issue.

Last but not least, look for any signs of bending in the clearances.

You may do this yourself or hire a mechanic to do it for you. However, determining whether or not there is a problem is rather straightforward. It’s also a good idea to remove the spark plug and see how the rocker arms move when you pull the recoil cord. If the valves do not shift positions, there is an issue that needs to be addressed.

Carbon deposition between the face and the seat is another prevalent problem with valves. If the build-up is present, it prevents the valves from closing properly, causing exhaust fumes to flow back to the carburettor.

Other Reason Why Generator Makes Popping Noise When Starting

Generators are frequently used in emergencies, such as when there is a power outage. As a result, storing it for some time is nearly unavoidable. However, you may find that it won’t start after being stored for a while, or that it makes a backfiring sound.

The most prevalent reasons for a backfire or after the fire have already been discussed. Now we’ll look at some of the other reasons for a backfire and why your generator won’t start.

  • Low on Oil
  • Fuel Tank is Empty 
  • Choke Lever is Incorrectly Positioned 
  • Fuel Valve is Shut
  • Carburettor Problems 
  • Dysfunctional Spark Plug
  • The battery may be dead.

Low on Oil

If a generator is low on oil, it will not start or will backfire. As a result, it’s critical to ensure that the oil is at the proper level frequently. In this process, a dipstick & generator maintenance kit will come in handy.

You should be aware, however, that putting the generator on an uneven surface will disrupt the oil flow. In this case, a levelling and protecting mate might come handy. The generator may have enough oil but is unable to detect it due to its orientation. As a result, make sure it’s always on an even platform. An antivibration pad can also be used to reduce the vibration on top of the levelling mat.

Material Needed
Leveling Mat
Anti-Vibration Pad
Generator Maintenance Kit

Fuel Tank is Empty

Your generator will most likely not start if it does not have enough gasoline. Also, if you try to run it on low gasoline, you can get some backfiring. As a result, it’s critical to add gasoline when it’s running low. Also, use fresh fuel to avoid clogging the combustion system parts of the generator.

Choke Lever is Incorrectly Positioned 

When starting the engine, make sure the fuel choke is in the proper position. When you’re getting ready to start the engine, it should be in the closed position. After it has fully warmed up for some time, you must switch it to an open position.

Fuel Valve is Shut

The position of your fuel valve could be the cause of your generator not starting or popping. The fuel flow from the tank to the carburettor is controlled by the valve. As a result, it should be open when starting the generator, particularly if the system had been depleted during a shutdown.

The fuel valve may be open, but the fuel is flowing unevenly to the carburettor. In this scenario, you should verify the vacuum relief valve’s position. It should be accessible. You can also check for a problem with the valve by pulling the gasoline cable from where it connects to the valve. If there is no fuel flowing but the valve is open, the valve is clogged can be unclogged by a fuel injector cleaner.

The gasoline filter is another important component to inspect. It may become blocked with time, especially if you’re using low-quality gasoline.

Material Needed
Fuel Injector Cleaner
Fuel Valve Pump

Carburettor Issues

The carburettor in your generator may be obstructed, especially if it has been kept for a long time. This is a regular problem when storing your generator without completely draining the fuel system. Fortunately, this is a simple repair. While the fuel valve is closed, open the carburettor drain valve.

Eliminate the lower half of the carburettor and clean it well with clean gasoline to remove the sediments. 

Material Needed
Carburetor Kit 

Dysfunctional Spark Plug

Your generator may occasionally fail to start due to a malfunctioning spark plug. If you’re certain that’s the problem, you can remove it and replace it with another. You can also clean it up by removing the carbon deposits on the portion that connects the crankcase to the engine.

It’s critical to check if it’s working once you’ve replaced or cleaned it. Connect the spark plug to the current supply first. Pull the recoil starter like you normally would start the engine. You should be holding the plug to the crankcase at this point. It will produce a blue flame if it is completely functional. If it doesn’t, check to see if the ignition coil is working.

If the ignition coil is in good working order, the problem is a spark

Material NeededTools
Spark PlugSpark Plug Socket


It is critical to keep your generator in good working order so that it does not fail you when you need it most. As a result, one of the most important aspects of keeping it in good working order is figuring out why it’s backfiring.

The problem might be caused by several factors. However, you must distinguish between backfiring and after firing, as they are two separate but linked problems. After firing, the punishment is not overly severe. However, a backfiring issue must be resolved quickly.

We’ve outlined the processes for correcting both. We’ve also included the most common reasons for your generator not starting. You must follow our advice and take the necessary safeguards that we have explained.

Frequently Asked Questions (FAQs)

Why is my generator making a popping sound when starting?

We have discussed all the possible reasons and their solutions in this blog following is the summary:

  • A carburettor with a restricted combination of air and gasoline
  • Fuel combustion begins early.
  • There’s a problem with the intake valve.
  • Low on Oil
  • Fuel Tank is Empty 
  • Choke Lever is Incorrectly Positioned 
  • Fuel Valve is Shut
  • Carburettor Problems 
  • Dysfunctional Spark Plug
  • The battery may be dead.

How do you fix a backfire on a generator?

Allow the generator to run for an hour on the lowest setting with nothing attached after setting it up and starting it for the first time. Drain the oil and replace it with fresh oil to help remove any debris that may have been shaken away. For another hour, keep it on low. Drain the oil and replenish it once again.

What sounds does a generator make?

When heard from 23 feet away, most portable generators have a noise level of 70 to 100 decibels. Remember that 100dB is eight times louder than 70dB, so there’s a big difference. 70 dB is about the same as the noise level at a crowded restaurant, while 100 dB is about the same as listening to an MP3 player at full blast.

Why is my generator sputtering?

With portable power generators, clogged air filters are a regular issue. If you use your generator in dusty locations like barns or construction sites, you should clean or replace your air filters regularly.

How long can you leave gas in a generator?

A decent fuel stabiliser can extend the life of the generator gasoline you’re storing by two or three times. Preppers will tell you that unadulterated diesel fuel can last for roughly a year if kept properly. But only if the weather is pleasant — approximately 70 degrees. The time limit increases shorter as the temperature rises.

Why does my generator rev up and down?

Fuel-related surges are typically produced by one of three factors: improper fuel, low fuel levels, or poor fuel quality. Most generators have certain fuel needs, and utilising any sort of fuel that isn’t within those constraints can result in operating problems, including surges.