7 Common Reasons Your Generator Won’t Start

Your generator may fail to start for various reasons, including a dead battery, low oil levels, low fuel levels, dirty air filters, spark plug issues, choke control problems, and carburetor blockage.

It is annoying when you want to start your generator, but it fails to respond, especially during emergencies when you need it the most. However, some good news for you is that troubleshooting unresponsive generators is easy as long as you know where to start looking. Because of this, we have outlined some of the most common reasons behind your generator failing to start and some solutions you can make.

Why would my generator fail to start?

Dead battery

This point mainly applies to generators that use electric starters, so the battery is always the first suspect if the generator fails to start. This is because the electric starter requires the battery to give it an energy boost.

To prove that the battery is the problem, you should use an auxiliary recoil starter to test it. If the recoil starter gives the generator enough starting power, that means the battery is dead and needs recharging. If you do not have the recoil starter, you can alternatively test the battery using an external charger.

Low oil levels

If the battery is full and the generator fails to start, the generator may have low oil levels. With this in mind, many modern generators have in-built precautionary measures to prevent this issue, like an auto shut-down mode when the oil levels are below safe levels or low oil sensors.

To confirm whether this is the issue, use a dipstick to check the oil levels and the manual to see the specific safe levels the generator needs.

Low fuel levels

The fuel levels are the third place to check in non-starting generators because the machine burns fuel to produce power. Diesel and gasoline generator fuel levels are easy to verify, but propane generators are trickier because of their design – they rely on a propane tank connected to their valves through several tubes. Gasoline generators can also suffer from low fuel levels or old fuel remaining in them, which damages their internal components.

Dirty air filter

For the generator to ignite its fuel supply and start the engine, it must have a continuous clean air supply. However, debris and dust will clog the air filter, which hinders unrestricted airflow to the carburetor, and the generator fails to start.

Issues with the spark plug

Like the air filter, a generator’s spark plug may be too clogged to work correctly. However, it is not as easy to access because you must first remove it from the socket. To test it, you can use a spark plug tester, which will only need cleaning if you see a spark. If the dirt levels are minor, you will not need to replace the plug – wash the debris and dirt off using a soft brush.

Choke control problems

The air levels in the generator’s carburetor are due to the air filter and the choke. If the choke control is too closed or too open, this will cause startup issues in the generator. You will notice it because the generator attempts to start but fails to turn over. This issue is prevalent with generators that have not been started for a while.

Carburetor blockage

Carburetor issues are closely tied to the choke because the carburetor is where the fuel and air mix, create combustion reactions, and allow the generator to produce electricity. Like choke control problems, problems in the carburetor mainly happen in irregularly-used generators, especially in portable generators.

This problem occurs when old fuel clogs the generator during storage and blocks the carburetor. The old fuel blocks the entry of new fuel into the carburetor, and internal combustion fails.

A summary of solutions for failure-to-start issues in generators

Problem Solution
Dead battery Test the battery using an auxiliary recoil starter or external battery charger, and see if it reignites the battery. If not, battery replacement is due.
Low oil levels Use a dipstick to see if the generator’s oil levels are safe, and refill it if they are below the recommended level.
Low fuel levels Check if the tubing and valves are open in a propane generator. In a gasoline generator, use a dipstick to check the fuel levels. Also, replace the fuel if it is older than 2 months.
Dirty air filter Regularly clean the air filter to remove dust and debris. If the problem is severe, replacement is due.
Spark plug problems Use a brush to clean the spark plug and electrodes. If the problem is severe, replacement is due.
Choke control (too open or too closed) Close the chokes when the generator engine is cold, then gradually open them entirely when it warms up.
Carburetor blockage Check the state of the fuel in the generator and replace it if needed. Empty the fuel if you will not use the generator for some time to prevent the issue.


While the abovementioned problems are more general in outlook, you should always check the guidelines your generator’s manufacturer outlines. Regardless of the problem you are dealing with, it is always best practice to enlist the help of a professional to repair the machine if you are unsure of how to do so or if it fails to start after checking the reasons above.


How long can generators run?

It depends on the generator’s fuel source. A portable propane generator can run up to 200 hours, while gasoline generators can run up to 16 hours at a time.

What can happen if water enters a generator?

Water is dangerous to the generator and its internal components because it interferes with electric connections and causes damage by creating corrosion and rust.

What can cause a generator to start slowly?

This could be due to several reasons, including defective batteries, bad starters, faulty electric connections, and battery rundown.

What can happen if a generator runs dry?

Likely, the magnetism in the coils is adversely affected when the generator runs dry, causing it not to restart.

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