Why Is My Generator Revving Up and Down? – [Top 13 Causes]

A generator that Rev up and down could not only wear out the generator’s organs but also provide Unstable outputs that can melt down your voltage-sensitive appliances within no time.

“Generator can rev up and down due to factors like low or stall fuel, clogged carburetor, overloading, bad ignition system, worn out rotor, blocked filters, etc.”

This guide is all about answering your burning quarries about why is my generator revving up and down and how can I fix it without spending a penny.

Why Is My Generator Revving Up and Down?

1. Clogged Carburetor:

The purpose of a carburetor is to provide a balanced air-to-fuel ratio to the combustion chamber to ensure a super smooth fluctuation-free operation.

If the carburetor is clogged an improper/lean air-to-fuel ratio will be fed to the combustion chamber causing backfiring, Sputtering, Revving up and down, fluctuated voltage, etc.

  • How to Fix It

Clean the carburetor’s main organs like the main jet, pilot jet; fluid pin, etc. Also, use a premium carb cleaner like STA-BIL Carb/Choke & Parts Cleaner to ensure there is no dirt or debris available in the fuel or air channel.

Recommended Read: How to fix a supettering generator?

2. Stall or Low Quality Fuel:

Low or stalled fuel will imbalance the combustion process causing the generator to rev up and down.

For a smoother operation, a generator must be fed with a decent amount of fresh fuel (high octane or at least with a fuel stabilizer).

  • How to Fix It

Check the fuel level of the generator; you can observe the fuel level from the fuel gauge, If the fuel is low, make sure to refill the generator.

Also if you suspect that you have poured stalled or old fuel that sits for more than 3 months, drain the old fuel and refill the generator with fresh high-octane fuel or normal fuel with a fuel stabilizer.

Old fuel tends to stall and absorb the moisture content that restricts the proper combustion process.

I mostly stick a piece of duct tape on the fuel container with the purchased date of the fuel to ensure my generator is fed with fresh fuel.

3. Overload:

If you are pulling more load than the generator’s capacity (starting and running watts), the generator becomes overloaded causing revving up and down, sputtering, backfiring, etc.

Suppose you own a generator of 3kw and you are pulling a 3.1 – 3.2kw load, the generator will surely overload and also can damage the voltage-sensitive appliances if it’s not equipped with overload protection.

  • How to Fix It
  • Remove all appliances and reset the generator.
  • Calculate the starting and running wattages of the appliances you are going to power.
  • Compare the calculated wattages with the generator you own, the calculated wattages shouldn’t be more than the generator’s power rating. we recommend keeping a margin of 10- 15% to not only save the fuel cost but also increase the longevity of the generator.

Recommended Read: How to fix an overloaded generator?

4. Bad Capacitor:

Generator capacitor
Generator capacitor

The purpose of a capacitor is to store the energy (charge) and supply it to the generator’s rotor when needed. Also, a capacitor is responsible for regulating the voltage as well.

  • How to Fix It
  • Shut off the generator and remove the capacitor located inside the end or stator cover.
  • Inspect its physical condition, if you find something damaged make sure to replace the capacitor.
  • If there is no physical damage, fire up the generator and take readings of the +VE and –VE wirings of the capacitor by using a millimeter.
  • If the reading is between 4 to 5 volts, the capacitor needs replacement.

5. Damaged Governor Rod:

Governor Rod of the generator
Governor Rod of the generator

The sole purpose of the governing rod is to control the RPMs/Speed of the generator’s engine; if it’s not functioning properly the generator may operate at uncontrolled RPMs and sounds like it’s revving up and down.

  • How to Fix It
  • Shut off the generator and locate the governor rod, mostly located on the side of the throttle adjustment screw.
  • Disconnect the governor rod and inspect its condition.
  • If you found it damaged, install a newer one, Also make sure to do the necessary adjustments by reading the user manual.

6. Clogged Fuel Filter

The fuel filter of the generator is adapted to block the dirt and debris and passes a super clean fuel to the carburetor for balanced combustion.

If the fuel filter is clogged there will be insufficient fuel available for burning and as a result the generator misfires, backfires, revs up and down, etc.

  • How to Fix It

Remove the fuel filter and inspect its condition, if it’s clogged make sure to clean it properly, also if you find something damaged, replace it as soon as possible. Here is the guide to clean the fuel filter of a generator in an instant.

7. Clogged Air Filter

Clogged air filter
Clogged air filter

The air filter holds the dirt and debris and passes the fresh clean air to the engine for not only proper combustion but also for cooling down the engine.

Blocked air filters could imbalance the air and fuel mixture causing the generator to vibrate, revive up and down, overheating, backfiring, etc.

  • How to Fix It

Remove the air filter from the air filter’s assembly, inspect its physical condition, and if you find damaged or cracked foam make sure to replace it.

Also if the air filter is too dirty, clean it with normal detergent water, here is the process to clean the generator’s air filter.

8. The Generator is Too Old:

An old generator may rev up and down because of worn-out essential components like the carburetor, rotor, alternator, combustion chamber, pistons, etc.

  • How to Fix It

Rather than spending hundreds of bucks on repairing, Purchase a brand new machine from reputable brands like Honda, Champion, DuroMax, or Westinghouse.

9. The Throttle Spring Is Missing or Detached:

A throttle spring is utilized to hold the throttle to the adjusted position, if it’s, detached or damaged, excessive air could be drawn into the engine, and as a result, the generator revs up and down.

  • How to Fix It
  • Shut off the generator and let it cool down.
  • Remove the spark plug and turn off the fuel valve for an added layer of safety.
  • Locate the throttle screw, if it’s attached make sure to inspect its physical condition and elasticity. If it’s worn out or damaged, make sure to replace it.
  • Also if you found it detached, Reattach it, and adjust the throttle position.

10. Worn Out Rotor:

Rotor of the generator
The rotor of the generator

The rotor is the most essential part of the generator responsible for generating current by rotating between the magnets.

If the rotor is worn out the engine will not get sufficient power and as a result, the generator starts vibrating, sputtering, or rev up and down.

  • How to Fix It
  • Turn off the generator and let it cool down.
  • Remove the generator’s End or stator cover.
  • Locate the rotor and disconnect its connections.
  • Test the rotor if it’s faulty, install a newer one.

11. Fuel Selector Switch Is Malfunctioning:

Fuel Selector switch
Fuel Selector switch

Most dual fuel generators have a fuel switch for a hassle-free fuel transition, however, if it malfunctions the gasoline and propane may be mixed causing improper combustion and leading to backfiring, sputtering, revving up and down, unsteady power, etc.

  • How to Fix It

Repairing a fuel selector may be a hectic task for a newbie we recommend seeking help from a professional unless your machine still has the warranty.

12. Bad Spark Plug or Ignition Coils:

A faulty spark plug or ignition coil can disturb the chain of combustion and as a result the generator misfires, backfires, revs up and down, or even harms the voltage-sensitive appliances because of the unstable voltage.

  • How to Fix It

Remove the spark plug and inspect its physical condition, if it’s dirty with excessive carbon deposits, make sure to clean it.

Furtermore, the spark plug should be replaced if you found it with a fouled or damaged electrode.

Here is the guide about cleaning or replacing the generator’s spark plug

13. Blocked or Restrictions in Exhaust System:

Clogged exhaust could reduce the performance of the engine causing, overheating, backfiring, lower output, rev up and down, etc.

  • How to Fix It
  • Turn off the generator and let it cool down.
  • Monitor the exhaust system, If you find carbon deposits, dirt, debris, or any other obstacle, make sure to clean it to restore the airflow.
  • If you find excessive rust or leaked muffler or pipes, make sure to repair it with a heat-resistant sealant or replace it, if the problem is worse.
  • Tight the loose parts so that there will be no leakage.

Note: If the problem is still there please contact the manufacturer or seek help from a professional generator mechanic.

Generator Revving Up And Down Under Load

Lean air to fuel mixture, Low/stall fuel, damaged governor rod, and detached throttle spring could be the main reason your generator is Revving Up And Down under the Load.

Honda Generator Revving Up and Down

Insufficient fuel supply, lean air to fuel mixture, overloading, and bad quality fuel could be the main reasons your Honda generator is revving up and down.

Using clean fresh fuel with a fuel stabilizer and routine cleanups of the fuel lines, filters, carburetor, and spark plug can fix the problem without hiring a mechanic; also make sure the generator shouldn’t be overloaded at any cost.

Final Words

Though there are a wide range of reasons why your generator is revving up and down, still clogged carburetor, stall/low fuel, overloading, bad governor rod, clogged filters, and bad ignition system are the main reasons that shouldn’t be overlooked.

Fortunately, fixing a revving up and down generator isn’t rocket science and you don’t have to hire even a professional in most cases, however, if the problem is still there after applying all the fixes listed above, don’t hesitate to hire a professional.  This will save your hundreds of bucks down the road.

I hope you are now able to fix a revving up and down generator without spending a penny, if I am missing something, please let me know in the comment section, and I will be more than happy to assist you



Kashif has been a valuable asset to the electric generator industry for over 5 years. Now, As a skilled energy engineer, he’s been on the front lines of diagnosing problems, fixing broken parts, and performing routine maintenance tasks to keep generators running smoothly.

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