Generator Backfire: Troubleshooting and Reasons — Port Washington, WI

When you try to start your generator, do you hear loud pops? The popping sound is a generator backfire, and it can be as loud as a balloon bursting or a gunshot. Depending on the state of your generator, flames or smoke may also shoot from the exhaust when it backfires.

The loud bangs can scare your neighbors into dialing 911 and even damage your generator. If you want to know why your generator keeps backfiring and won’t start, the expert team at Professional Services in Port Washington, WI, has provided you with some answers right here.

Common Causes of Generator Backfire

1. Low Oil

Like a car, your generator needs oil to reduce friction within its engine. Get the best results by filling your generator with clean, good-quality oil and place the machine on an even surface. However, do not overfill the generator with oil, as this may disrupt the unit’s performance.

Should your generator backfire when you try to start it, check the oil dipstick. If the oil is dark and gritty from months of usage, it may be why your generator is backfiring or not starting. Low oil levels can also stop your generator from starting.

2. Old or Dirty Fuel

Is your generator not starting? It may be because the fuel level is low. However, if the system is backfiring, the fuel in the gas tank may be old or dirty. Leaving fuel in your gas tank for months will cause it to degrade. Degraded or stale fuel is less flammable. Fuel is also less combustible when it mixes with water, oil, or other contaminants.

If gasoline doesn’t burn the way it should, it will negatively impact the performance of a combustion system and may cause backfiring. Avoid such issues by siphoning old or dirt fuel from your generator and replacing it with clean, fresh fuel.

3. Open Choke Valve

Your generator has a choke valve for stopping air intake before starting the engine. If the valve is open, your generator’s combustion engine won’t get enough fuel to ignite, leading to backfiring and the engine not starting.

Close the choke before starting the generator, then open it once the generator is running. If you leave the choke closed after starting the generator, the unit won’t run smoothly and may eventually stall.

4. Closed Fuel Valve

The fuel valve controls the fuel line that transfers gas from the tank to the combustion system. Closing the fuel line will stop your generator from getting the gas it needs to start and run. As the engine tries to run with the little gas it has, it will sputter and backfire.

5. Clogged or Damaged Fuel Line

A closed fuel valve isn’t the only thing that can stop your generator from getting enough gas. A clogged, pinched, or leaking fuel line may also lead to insufficient gas reaching the combustion system.

A clog may occur due to debris from the gas tank accumulating within the fuel line. Leaking cracks in the fuel line can be because of years of exposure to the elements.

You must replace a leaking fuel line, but you can fix a clog by simply flushing the gas tank and fuel line. Repairing a pinched line is much easier since you only need to untangle and readjust it to facilitate the free flow of fuel.

6. Clogged Carburetor

Some generator manuals recommend running your generator at least once a month, while others recommend once a week. If you do not run a fueled generator for months, the fuel can clog the carburetor.

As we mentioned earlier, fuel left in the gas tank will gradually degrade and become less flammable. If this fuel gets into the carburetor, it can clog it and stop fresh, ignitable fuel from entering. As the engine tries to ignite the degraded fuel, it may backfire.

Prevent such issues by emptying your fuel tank before storing your generator. If you choose to leave the fuel inside the generator, you must run the unit at least once a month.

Running a generator every month is better than emptying its fuel tank. That’s because running the generator allows you to verify that the system is working well and that you can count on it for power during a power outage.

7. Lean Fuel-to-Air Ratio

If your generator has a lean fuel-to-air ratio, it will cause slow combustion. During slow combustion, the combustion process cannot keep up with the air and fuel mixing in the combustion chamber. When this happens, and the exhaust valve isn’t open, it leads to valve overlap, and the generator will backfire.

Your generator’s lean fuel-to-air condition may be because of a dirty, old, or improperly adjusted carburetor.

8. Bad Spark Plug

A spark plug facilitates the ignition needed to start a combustion engine. It works by generating sparks that ignite compressed fuel to start the engine. Over time, a spark plug will wear out and become dirty. When this happens, the combustion system won’t get the spark it needs, leading to timing issues and your generator backfiring. If your spark plug is causing your generator to backfire, replace it.

How Do You Fix a Backfire?

The right way to fix a generator backfire depends on what’s causing the problem. For example, a generator that backfires after it drops from a high RPM to a lower RPM when switched off may not need repairs. However, a generator that backfires during start-up or while running may need repairs.

Instead of repairing your generator yourself, save money and get reliable results by calling for generator repair from Professional Services. Our team in Port Washington, WI, has years of experience repairing gas, propane, and diesel generators from various brands.

We are available 24/7 to provide emergency generator repair whenever you need it. Our well-equipped vans contain everything we need to fix generator backfire and other issues within a single visit. We also provide generator maintenance services that will keep your unit fuel-efficient and running smoothly for years.

Call our Professional Services team today at (262) 214-5548 to schedule a consultation or emergency generator repair in Port Washington, WI.