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Generator Dies Under Load: Likely Cause and How to Fix It

Why does a generator die when it's under load?

When a generator starts and idles just fine, but then dies under load, it usually indicates a fuel delivery issue. My neighbor ran into this issue recently. Let’s make sure that you know what to do if it happens to you.

If your generator is continuously dying under load, it’s likely due to a clogged carburetor. When the passageways of your carburetor become clogged, it ends up blocking gas from getting to the engine. Other causes include a clogged fuel or air filter.

In this article, we’ll be going more in-depth into why your generator dies under load, and how exactly you can fix this and keep it from happening in the future.

Why Is My Generator Dying Under Load? 

Think of this way. Your generator starts and idles, so it is getting fuel. But once you increase the demand for fuel by adding an energy load, the fuel system is no longer able to keep up.

The carburetor is the common culprit as it’s prone to become clogged with varnish.

Let’s get clear on what you need to understand about fuel varnish and how it affects your carburetor in the long run. 

  • Varnish can begin to form when the gas within the engine becomes too old.
  • This causes unwanted build up, and can cause gas to become stuck and unable to reach the engine. 
  • It’s important to note that gasoline formulation can go bad in as little as 30 days, so it’s ideal to change out your oil when the time comes, as opposed to having it sit there for too long.
  • Varnish won’t build up on your equipment overnight, but over time it will begin to build, leaving problems for you and your generator in the future. 
  • Ensure your tank isn’t filled up with old gas, and clean the carburetor often. 
  • This can even happen to those who have just purchased a brand new engine. During the manufacturing period, carburetors are not commonly cleaned in the warehouses where they are being built.

Varnish building up within your generator can cause even more problems such as oil overflowing on the engine (sourceOpens in a new tab.

How to Fix Your Generator So That It Doesn’t Die Under Load

As stated above, your best bet is to either replace your carburetor or simply give your equipment a good and thorough cleaning. I tend to lean toward cleaning first. It can save you some money and a lot of times, that’s all that is needed.

Take a Picture Before to Make Reassembling Easier 

Before you remove your carburetor, it’s recommended that you snap a picture of it, still attached to all it’s springs and plugs, as this will make reassembling your machinery afterward much easier. 

I’m a big believer in taking multiple pictures along the way as I disassemble. This helps me to track my steps backward when rebuilding.

It’s important to note that if you plan on keeping and cleaning your old carburetor, removing months or years of buildup will take longer than a few minutes. This is definitely a task that involves a lot of time and patience, so it’s important to be mindful of that.

Remove Your Carburetor and Clean It With a Solvent 

To properly clean your carburetor, you’ll need to completely remove it, as well as all the non-metal parts attached to it, and allow it to soak in solvent for several hours. If you’re looking for the best possible results, soaking it overnight is even better.

If you’re looking for the ideal commercial solvent that will help you get the job done, this STA-BIL 22304 Fast Fix Engine TreatmentOpens in a new tab.

I’m a big fan of Gumout Carb and Choke CleanerOpens in a new tab.

Wear the Proper Safety Gear While Cleaning 

While performing this step, it’s ideal to wear gloves and/or goggles, as using a generous amount of this spray is likely to get messy.

Apply a good amount of cleaner spray to your carburetor, dry it off with low pressure compressed air. Once your equipment is completely dry, it’s time to begin reassembling your equipment. 

Use the Picture You Took Earlier to Help With Reassembling

This is where the picture you took earlier will come in handy, as it will be much more difficult to reassemble your machinery correctly without any type of reference.

Of course, these are the steps you were to follow if you choose to keep your old carburetor, while some may choose to invest in a new oneOpens in a new tab.

It’s also important to be mindful that sometimes even a proper cleaning won’t do the trick, and you’ll have to invest in a new carburetor anyway, so be prepared for that.

Thankfully, you have all the tools you need if this were to be the case. 

This video walks through the cleaning process for a carburetor. Although the discussion is about Champion generators, you’ll find that the basic parts of a generator carburetor is very similar.

Champion Help Center: Cleaning the Carburetor in your Generator or Inverter

How to Avoid This Problem in the Future

Now that you’ve learned more about why your generator reacts this way, how can you avoid this problem moving forward?

Well, for starters, as we stated earlier, it’s ideal to not let your gas sit for too long. Your gas can go bad in as little as 30 days, and after that time period, varnish can begin to build and cause problems for you and your machinery.

My practice is to completely drain the fuel tank and run the generator until it dies, depleting any remaining fuel in the system. I do this anytime I’m expecting to store it.

It’s also recommended to check on your carburetor regularly to see what kind of condition it’s in. If enough build up has begun to form over the course of a few months or even a few years, this can begin to show on your carburetor. 

Taking all these factors into consideration is vital to keeping your generator moving and working as it should be. 


When your generator is continuously dying under load, the issue often lies in the carburetor. It is likely that varnish has begun to build up within that area, and it’s causing gas to be blocked from traveling to the engine.

Clogged air filters or fuel filters can also cause this issue so don’t overlook those. The truth is, I’d rather it be the fuel filter than the carburetor on any day but I have seen this issue enough to realize that the carbs are usually the culprit.

Use quality fuel and don’t leave it in the tank stored unless you are including a fuel stabilizer such as StabilOpens in a new tab.

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As a homeowner, I am constantly experimenting with making the structure of my house more energy-efficient, eliminating pests, and taking on DIY home improvement projects. Over the past two decades, my family has rehabbed houses and contracted new home builds and I've learned a lot along the way. I share my hard-learned lessons so that you can save time and money by not repeating my mistakes.

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