Generac Generator Troubleshooting

Generac generators are some of the best generators on the market today. They are a popular choice for many homeowners and businesses. With so many different models to choose from, there is a perfect one for every homeowner. The manufacturer offers both portable and standby models. Both options can be helpful during power outages or when you need to power up your business, home, or meet outdoor power demands. 

However, sometimes the Generac generator won’t start up correctly, which is frustrating! The malfunctioning could be because of several reasons, including low oil levels, a clogged fuel cap vent, or even a dirty air filter. So, how do you get back your Generac generator into its best state? Read on to learn how to troubleshoot a Generac generator.

Common Problems with Generac Generators

Every generator brand has its quirks, and Generac generators are no different. Here are some of the most common problems people experience with their Generac generators:


  1. The generator won’t start


If your Generac generator doesn’t turn on, it may be due to a low oil level. The cause of this could be that you haven’t checked the oil in quite some time, or there is an issue with the dipstick or gauge readings. To check if the engine has enough oil for operation:

  • Unscrew the oil tank and check the oil level using the modified lid as a dipstick. Wipe it clean and reinsert it to check the oil level. 
  • Make sure you check both sides of the stick. There should be oil on both ends; check the oil mark by looking at the readings on the dipstick. If oil is not visible, the engine is low on oil. Top up using recommended oil before you try to restart the generator again.


Other areas to check when a Generac generator does not start are:

  • Loose connections: Clean and tighten any loose connections on the generator. You can also remove the ground terminal from the generator’s frame to check if it is corroded.
  • Generator’s safety lock switch: Inspect the safety interlock switches and ensure they are not bent. You can also test the effectiveness of the safety lock switch using a multimeter.
  • Recoil starter: This part is responsible for engaging the crankshaft to start the engine. A defective recoil starter will not engage the crankshaft as it is required. This means the generator will not start. Inspect the recoil starter by removing the starter assembly and checking whether it is working correctly. Pull the starter rope and check whether it will make the engine turn. 


Release the rope and check whether the tab will retract and unwind the rope back on the pulley. If it doesn’t make the engine turn or rewind the rope, the recoil starter is defective and requires rebuilding or a replacement. 


  • Carburetor: The carburetor can easily clog. If you store your generator with fuel for a long period, some of the elements in the fuel evaporate, leaving a dense substance. This thick substance can clog the carburetor and prevent the generator from starting. 


You can restore a clogged carburetor by cleaning it using a carburetor cleaner. If this doesn’t help, you may need a technician to rebuild it or replace the clogged carburetor with a new one.


  • Spark plugs:  Inspect the spark plugs for signs of wearing out. If you find the porcelain insulator on the spark plug is damaged, cracked or accumulated carbon on the electrode, the spark plugs won’t work. 

You can test the effectiveness of a spark plug using a spark plug tester. If the spark plug does not produce any sparks when testing it, then it’s defective and you’ll need to replace it.


Spark plugs are vital in the starting of any generator. If the spark plugs are faulty in any of your Generac generators, the generator will not start. In some cases, the generator may start and shut down almost immediately but with a crackling sound.


  • Ignition coil: This part is responsible for sending voltage to the spark plug once the engine starts running. When you have a defective engine coil, the engine may fail to start. However, before you rush to replace the engine coil, you must ascertain that the spark plug is in its perfect condition. Proceed to test the effectiveness of the ignition coil using an ignition tester. If it’s defective, the generator cannot run without an ignition coil; proceed to replace it.


  • Flywheel key: A small key fixed into the crankshaft to engage the flywheel. This key may break into two if your generator stops running suddenly. A broken flywheel key may cause inconsistencies when starting your generator. You can inspect a broken flywheel key by removing the flywheel from the engine. If you ascertain the flywheel key is broken, you will need to replace it.


  1. The engine runs rough or makes strange noises

If the engine is running rough or making strange noises, it could be a dirty air filter, clogged carburetor, and faulty spark plugs. To troubleshoot:

  • Check on the carburetor and the spark plugs as detailed in the above section.


  • Fuel filter: The generator can rough or make strange noise if the chainsaw runs poorly. This is one of the signs of a clogged fuel filter. The clogging in the fuel filter occurs when the chainsaw is left with old fuel over a long time. The clogging process of the fuel filter is similar to that of the carburetor. And it will cause the engine to run with noise or even stop running. If old fuel is left on the chainsaw for a long period, empty the fuel tank and replace the fuel filter with a new one.


  • Air filter: Generators require air for full combustion to take place in the engine and release power. Air filters allow oxygen into the combustion chamber and block dust and other particles into the chamber. When the air filters are blocked by dirt or are damaged, there will be restrictions on airflow into the engine, making the generator unable to operate optimally.  Inspect the air filters, clean and replace them when necessary.


III. Generator battery keeps dying

generac generator troubleshootingIf the battery on your Generac generator is dying, it may be because of a faulty voltage regulator or a faulty charging system. You can troubleshoot your battery by:

  • Checking the voltage regulator: A voltage regulator sends the correct voltage from the alternator to the generator’s battery to recharge it as the generator is running. If the voltage regulator malfunctions, the battery wil not receive the correct amount of voltage required to recharge it. This makes the battery lose its charge within a short time.


You can test the voltage regulator effectiveness using a multimeter. Connect the relevant cables of the multimeter to the generator’s battery. And monitor the multimeter readings; if th battery is healthy, the multimeter will display a voltage reading of more than six but less than seven. Any reading below six means signals a defective or uncharged battery; recharge it before proceeding with the test.


With the cables hooked to the generator battery and multimeter, start the generator and watch the multimeter readings. The multimeter readings should increase to about 7.4 volts when the generator idles. Increase the engine speed (RPM) and watch the readings on the multimeter. The readings should increase to about 7.8 or 8 volts and stop there. If the readings continue increasing to 8.2 volts, your generator regulator is faulty. Consider getting a replacement.


  • Alternator: You can test a faulty alternator using a multimeter. Start by checking the voltage readings of your generator battery; while the generator is not running, the readings should be around 12.6 volts. This reading is for a healthy battery. Start the generator and watch the readings changing. If the readings change to about 14.2 to 14.7 volts, your generator alternator is in its best shape. However, if the readings are below 14.2 volts or above 14.7 volts, the alternator is faulty. A faulty alternator can either undercharge your battery or overcharge it. The latter can damage your battery within a short time.


Tips for Keeping Your Generac Generator in Good Condition

For your Generac generator to deliver optimal performance, you must keep it in good condition. Here are some tips:


  • Periodically check the oil level and add if needed (only use the recommended oil type).
  • Clean the air filter every few months or as recommended in the user manual. 
  • Do not store the generator for long periods with fuel in the carburetor, fuel tank or even inthe chainsaw. If you have to store fuel, ensure to add a fuel stabilizer.
  • If you are not planning to use the generator for a long period, ensure to run it for about ten minutes at least once in two months. Doing so will keep the starter battery charged and the engine parts oiled.
  • Check out your Generac generator’s fuel lines. Long usage of generators can make the fuel lines tear, damage or even clog, interfering with the normal supply of fuel into the fuel system


Video On Generac Generator Maintenance  Tips

Frequently Asked Questions

What causes Generac generators not to start?

One of the main reasons why your Generac generator won’t start is the use of stale or old fuel. A generator that has been in storage with fuel for more than 30 days without fuel stabilizers can easily clog your carburetor. Similarly, a generator that has been stored with fuel with a stabilizer for more than six months can also clog the carburetor. You will have to clean the carburetor using a carburetor cleaner. If the problem is not solved, consult a Generac authorized technician for servicing.


Once the carburetor is clean, check your generator’s fuel tank, ensure it is at least a quarter tank. Open the fuel valve but before you start the engine, check the oil level. Proceed to check whether the spark plug wires are correctly attached and set the choke throttle into the right position. Ensure there are no appliances plugged in before starting the generator. Your generator should be ready to start now.

 What does red light on Generac generator mean?

A red light on your Generac generator signals that the generator will not power on in case of an outage. In most cases, there could be a fault that needs to be checked. Contact an authorized dealer for service if you cannot troubleshoot the generator.

 Why did my Generac generator stop working?

If the unit is correctly set for use but stops running each time you start it, check out the circuit breakers. They might have tripped. Check if the circuit breaker button is popped out and press it in to re-engage the circuit breaker. The generators should be ready to start.

  What does a yellow and green light mean on my Generac generator?

A yellow light on your Generac generators signals that the generator is due for maintenance. However, the generator will continue running as it has been programmed. A green light means that your Generac unit is running correctly. 

 How do I clear the yellow light on my Generac generator?

Yellow light on a Generac generator occurs to remind the user that maintenance is due. The reminders could be spark plug inspection, oil filter cleaning or change, among other maintenance exercises required on the generator. This light can be reset by long-pressing the Enter key found on the control panel.


  1. How do I manually turn on my Generac generator?

If your generator does not start automatically after a power outage, you must clear the fault. Start by opening the top cover of the generator and locate the auto manual off generator control found on the right side of the unit. Press the Off button followed by the Enter key to clear the fault code. Proceed to switch on the generator manually by pressing the manual button on the control panel, and this should start the generator.


Final Word

Generac is a reputable brand of portable band standby generators. However,  they are not immune to problems. By following the troubleshooting tips in this article, you can solve many common issues with your Generac generator. If you are still experiencing problems, contact an authorized technician for service.



About Steve Stuart

Steve Stuart is an electrical engineer who developed interest on generators during his school years. After school, he became a generator enthusiast. This is after encountering power supply problems at the area of residence where he lived. Power would be on and off and so food would go bad and the room heater would go off especially during winter. After trying the different generator brands for several years, Steve now provides information on the available brands and products in the market today. Based on his experience, he gives the do’s and the don’ts when it comes to generator use.

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