11 Reasons Your Generator Won’t Start and What to Do About Them

Reasons Your Generator Won't Start and What to Do About Them

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If you ever have a power outage and are disconnected from your local power supply, having a backup generator is always a good idea. Moreover, if you live off the grid, then having a generator is probably your only viable option to supply your home with electricity. It is, of course, a must-have if you need to use corded power tools on a jobsite without power outlets as well.

That said, generators can be a bit fickle. They are super useful, no doubt, but there is a host of problems that they can suffer from. Today, we are here to figure out why your generator is not starting, and what you can do to solve the problem.

#1: It’s Low on Gas

One of the most common reasons for a generator not starting is if it is low on gas or fuel. This is kind of a funny problem, because it’s the most obvious one, yet many people take a while to think about it. So, first off, check to see if there is gas in the fuel tank. If you are using a propane powered generator, check the propane tank to see if it has enough gas in it.

Either way, check to see that your generator has a solid supply of fuel that can power it.

On a side note, keep in mind that very stale gasoline can not only damage the motor, but may also result in the generator not turning on to begin with. If your generator has old gas in it, you may need to drain it out and replace it with fresh gas.

#2: It’s Low on Oil

Just like with gas, generators also need oil to function. Without oil, that motor will start to grind on itself and burn up. Most modern generators come with low oil sensors to tell you when there is not enough oil left. If you do not have a model with a low oil sensor, use the dipstick to check how much oil there is, and if there isn’t enough, you can take a wild guess at what needs to be done.

Just so you know, most generators will require more oil every 50 hours of use, roughly, depending on your exact generator and its oil tank capacity.

Oil for Power Generator

#3: The Battery is Dead

To start the motor of the generator, just like with your car, a battery is required (this does not apply to pull start generators with ripcords, like a chainsaw or other gas power tools). Some generators, although not all, have an electric start feature, sometimes with a button and sometimes with a remote.

If you have a specialized voltmeter, you could measure to see if the battery has a charge. However, if you do not have one of these tools, you can always just try charging the battery to see if that works. If you have a recoil starter on your generator, you can charge the battery using a 12-volt DC outlet. If you do not have a recoil starter, you can charge the battery with a 12-volt DC outlet in your car, or with an AC outlet (and an AC/DC converter). You may also use the jumper cables from your car to start a dead generator battery.

Keep in mind that batteries do not last forever, so there may come a time when the battery just needs to be totally replaced.

#4: The Carburetor is Clogged

One of the most common reasons for generators not starting is due to clogged carburetors, which often happens when generators are not used or put away from a couple of months with gas left in the lines. Old gasoline will become partially solid and form clogs, thus not allowing new gas to flow.

If this is the problem, the solution is to close the fuel valve, and then remove the bowl by the bottom of the carburetor. You can then use various tools like needles, towels, and brushes to clean and unclog the carburetor. Before you try starting the generator again, make sure to turn the fuel valve back on.

#5: There Are Cables Plugged In

Another common reason why your generator may not be turning on is because you have cables and electronics plugged into it. Most generators will not start when there is something plugged into them, as electronics should only be plugged in once the generator is already running.

Check to see if there are cables plugged in, and if there are, unplug them.

#6: The Choke Is in the Wrong Position

Yet another common reason why your generator may not start is that the choke is in the wrong position, and yes, it can either be too open or too closed. The position of the choke determines how much air is being mixed with the fuel for combustion, and either too much or too little air can cause the generator to not turn on.

If your generator has not been active for a few hours or longer, the choke should be 100% closed. If your generator has not run for a while, move the choke to the “starting” position. However, if your generator was running recently, and it just turned off for a few minutes, and now it will not restart, try moving the choke to either halfway or fully open.

#7: Spark Plug Issues

If the motor of the generator is not turning over, the issue could be with the spark plug. First off, make sure that the spark plug is properly plugged in. You can try removing it and then putting it back. If you see that there is a bunch of dirt and debris on the spark plug or the receptacle, clean the debris away.

The spark plug needs to have a solid connection to function. As such, if there is rust or debris that cannot be wiped away, if the spark plug is damaged, or if it is corroded, you will need to replace it with a new spark plug.

To check if your spark plug is working, you can hold it against the crankcase of the engine and pull the recoil starter (if your generator has a recoil starter). If the spark plug works, you will see blue sparks. If you do not see blue sparks, the spark plug does not work and will need to be replaced.

Power Generator Spark Plug Problem

#8: The Air Filter Needs Cleaning or Replacing

Something else that may be to blame here is a clogged or dirty air filter.

The air filter is required to keep the motor clean and free of debris. If there is too much dirt and dust on the air filter, it will be clogged, which will lead to not enough air getting into the carburetor, and there won’t be enough air for the fuel to combust. In most cases, air filters for generators cannot be cleaned and will need to be replaced.

#9: A Clogged Fuel Line

Besides a clogged carburetor, another area where a clog can occur is in the fuel line. Just like the with carburetor, if gas is left in the fuel line for too long, it can become chunky or even solid, and may cause a clog. To see if this is the case, remove the fuel line and hold it over a bucket, just to catch any fuel that comes out.

Check to see if fuel can flow freely through the fuel line. If it is clogged, you will need to unclog it, which you may be able to do with pressured air or by forcing water through it. If this does not work, you may need to replace the fuel line.

#10: Malfunctioning Sensors

The other main reason why a generator may not start is if the oil sensors are malfunctioning. No matter if the oil tank is full, if the sensor does not work, the generator will not start. Remember that if a generator sits on uneven ground, it will mess with the sensor, so if your generator is sitting on uneven ground, an easy solution is to level it out.

You can also check to see if the oil sensor is to blame by unplugging it from the crank case. If the generator starts, the oil sensor was to blame. If you can get the generator to start, run it for a few minutes, and then plug the oil sensor back in. It should work now. If this does not work, you will need to get the sensor repaired or replaced.

#11: It’s Old and Damaged

Finally, just like with any other product out there, generators don’t last forever.

They can (in rare cases) get hit by lighting (make sure your generator is properly grounded before use), they may suffer from water damage, or they may have suffered from physical damage due to falling debris. Sometimes motors just get old and wear out, especially if you run them for too long. Simply put, check to see that all major components are in good condition and not damaged.

If anything is damaged, repair it if possible, and, if not, replace it.

Replace Power Generator


The bottom line is that there are many reasons why your generator may not start. It’s up to you to engage in some good old trial and error to figure it out.

If you cannot figure it out, you will need to contact a professional.