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Generator Surging With No Load: What to Do?

generator surging no load
Written by Jamie Masterson

A generator surge when there is no load is common, but it is a sign that something is wrong with your generator. You can find the problem with some investigation and most likely fix it yourself.

Here we will look at what causes a generator to surge with no load and solutions to fix these problems.

Surge explained

The sound of a surging generator is speeding up and then slowing down because it works harder to get gas to the motor. You may notice lights getting dim and then really bright.

This intermittent power flow is not good for your lights or appliances plugged into the generator and is definitely not ideal for your generator.

Sources of No-Load Surges

  • Poor generator maintenance

A generator is a motor, and all engines require maintenance. A poorly maintained generator has a short work life!

Generators don’t last forever. If your generator is old and surging is a frequent problem, it could be time to buy a new generator!


All of the solutions below will help you keep your generator well maintained and possibly increase the life of your generator.

You don’t want to find out in a storm that your generator isn’t going to work.

  • Loose carburetor bolts and nuts

The vibration of a generator will loosen nuts and bolts over time. Nuts and bolts attached to the carburetor allow air to seep into the fuel, causing fuel thirst.

You can hear the intermittent surging as the generator fights to get more gas.


Loose hardware is an easy fix. Tighten the nuts and bolts. Grab a wrench and check the nuts and bolts near the carburetor.

Don’t make them too tight, but they need to be firmly snugged so they don’t loosen up when you restart the generator.

  • Poorly gapped spark plugs

Poorly gapped spark plugs won’t ignite anything and will cause the motor to misfire. The misfiring causes the surges; just like a car engine misfiring, it is bad for the motor.


Regapping your spark plugs. Using a spark plug wrench, pull the spark plugs out. Use a wire brush to clean off any deposits or dirt that will negatively affect the plugs.

Plugs need gapping between .028 and .060 (the space between the side of the spark plug and the ground strap.) You can find the gap requirements for your vehicle in the owner’s manual.

Using a feeler gap gauge, measure the space once you file the ground strap. It may need to be done several times before you get the gap right. If the gap is too wide, you can pinch the strap with needlenose pliers to create a smaller gap.

Once the plug is gapped, pop it into place and retighten using the spark plug wrench.

  • Dirty and old gas

The older the fuel, the dirtier it gets. Once the fuel has been contaminated, it needs to be replaced. The dirt and contamination will create surges that worsen as the gas ages.


You’ll need to empty the gas tank and refill it with clean fuel. Be sure to do this in a well-ventilated area and use a large container to catch 6 – 11 gallons of gas.

Remove the gas cap on the generator so air can get into the tank. Remove the two bolts holding the maintenance cover with the fuel valve off. You should see aluminum clips.

Leaving the clip attached to the gas tank in place, remove the other clip. Catch any fuel in the tube with an old cloth while removing the line from the gas valve.

Remember that if you pull the tube out completely, gas will go everywhere!

Once the fuel valve is on, you can drain the fuel tube into your container, ensuring the gas tank is empty.

When all the gas has drained, put the gas valve in its place, resecure the maintenance cover, and refill with fresh gas.

  • Flooded carburetor

If the shut-off valve remains open when the generator is off, or you start an already running generator, too much gas to the engine will flood the carburetor. You must drain the carburetor to prevent surging.


To drain the carburetor, locate the nut on the carburetor bowl and remove it.

Drain the fuel in the bowl into a gas-safe container. If you’re unsure where the bowl is found, check the manual.

Replace the bowl, rebolt it in place and restart the generator. The remaining fuel will burn up as the generator runs!

  • Wrong fuel filter for your generator

It’s imperative to use the fuel filter the manufacturer recommends. You also need to be sure the filter and type of gas you use match.

You should never use a gasoline filter on a diesel engine.

Your owner’s manual has the fuel filter information, so it’s best to check before replacing a fuel filter.


Make sure the gas filter and gas are the same. You also must ensure the filter is the correct size so it fits tightly to avoid fuel leaking and creating a surge.

  • Governor is not adjusted

A governor adjusts engine speed, so the generator will surge if it needs fine-tuning or isn’t working correctly.

The motor runs faster the lower you set the governor, so if you don’t want surges, you must ensure it is appropriately set.


Since each generator has its own settings, you must refer to the manual.

Keep in mind that this is a complicated fix, so we recommend taking the generator to a service center if you have never done this before.

  • Wrong air/fuel mixture

As with any engine, the wrong air/fuel mix will affect how hot the motor gets, which will cause surging during idle. A lean mixture is usually the issue.


Most times, you just need to adjust the screw to adjust the mixture. It is located on the side of the carburetor with a spring nearby.

If the mixture is too lean, you loosen the screw letting in more air.

Use a flathead screwdriver to turn the screw counterclockwise. You want it to be loose but not removed or too open to have an air-rich mixture.

  • Old carburetor seat or needle

Generator parts get old and tired. Once worn, they cease to do their jobs. A fuel system leak is caused when the seat or needle no longer functions properly.

Since they depend on each other to regulate the fuel stream, if one or both are not working, the increased stream causes the engine to surge.


The obvious solution is to replace the seat, needle, or both. Since they work together, you risk surging again if one isn’t working.

Changing the carburetor needle and seat simultaneously is recommended to eliminate the surging.

This is a straightforward process that any DIYer can handle. Loosen and remove the nut securing the carburetor bowl, then remove the bowl.

To remove the old needle and seat, you can use a flathead screwdriver to pull it out of the carburetor body. Pop in the new needle and seat.

Make sure they are snug before placing the carburetor bowl in place and retightening tight the nut and bowl.

  • Fuel filter clog

If your generator is losing power during a load, runs but has no power, or is stalling or sputters, chances are the fuel filter is clogged or is dirty.

The clog is impairing the fuel stream, so the engine is running lean, leading to it surging.


Replacing the fuel filter is the best solution. You have a clean fuel filter that is compatible with your generator.

Replacing the filter ensures you have eliminated the surging. The manual will have the how-to for changing the filter.

If you haven’t done this before, this video below will help. If you are unsure, a professional filter change is your best bet!

  • Clogged idle jet

The area where the fuel passes into the carburetor is regulated by an idle jet.

When the idle jet is clogged, the fuel flow decreases, resulting in a surge, especially when the generator idles.


Cleaning the idle jet is the solution. Loosen and remove the carburetor bowl bolt and the bowl. Then remove the float assembly.

Examine the float assembly while you have it out to ensure sure it is working correctly.

Spray carburetor cleaner on the idle jet and allow it to dry. If you don’t have the cleaner, you can use a compressor to blow the idle jet clean.

Once the idle jet is clean, replace the float and the carburetor bowl and retighten the nut on the bowl.

  • Low on oil

A reduction in oil increases friction and has the engine running hotter. The increase in engine heat will have it surging on idle just as if the oil is dirty.


Checking the oil to ensure it is clean and filled as the manufacturer recommends. The manual will show the type and amount of oil you should use and the dipstick location.

Once you locate the dipstick, pull it out and wipe it off with a rag.

Reinsert and remove it to check the oil level and see how clean the oil is. Dark brown to black oil is dirty and should be replaced.

If the oil is low, fill it to the fill line but don’t overfill it with oil.

  • Extreme cold

Frigid temperatures are brutal on a generator. The colder air causes the fuel to thicken and clogs the fuel filter, making the generator work harder.

The decrease in gas and its thickness cause the surges. Running the generator cold will decrease the life of the generator.


Get the generator warm before plugging anything into it. Once the generator is connected to your power source, let it run until the engine is warm (not hot!)

When the unit is warm, you can plug in the appliances and flip their switches on one device at a time.

About the author

Jamie Masterson

With decade-long experience as a generator technician, Jamie has worked with USA’s top generator manufacturers and suppliers as an independent contractor.

The long years of service to the industry has taught Jamie the ins and outs of troubleshooting, repairing, and maintaining all kinds of generators in home, industrial and outdoor settings.

Jamie thinks this platform is a great opportunity to share his tips and tricks with you so you can make the most of such power equipment for better living.

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