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Top 11 Reasons Why Your Generator Won’t Start & What to Do?

Last Updated: August 8, 2022
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The easiest way to figure out why your generator won’t start is to check out the top common causes. Many times a simple problem can be solved by fixing a small things, so make sure to fix any potential issues before your generator breaks.

Reasons Your Generator won’t start

1. Dead Battery

The battery is one of the most common causes of starting problems. Check to make sure the battery for the starter is the problem. If the battery for the starter is dead, the easiest thing to do is to use the 12-volt DC outlet on the generator to recharge the electric starter’s battery, which will allow the electric starter to fire again. If you don’t have a recoil starter on your generator, you’ll need to charge up the battery. You can use your car battery to jump-start your generator.

Jumper cables are useful for jumping your generator’s battery to the battery of your car. Use the metal frame of your generator as the fourth connecting point to link the cords to your automobile and generator.

2. Engine Oil

When oil levels are low, most generators have a sensor that will automatically shut down the generator. It is possible that low oil is the cause of the generator’s starting problems. The oil level should be checked with the dipstick. If the level is low, oil should be added.

If you try to run the generator on an uneven surface, the low-oil sensor might be triggered even though there is enough oil. If the oil is low, be sure to check your manufacturer’s guidelines on what type of engine oil is appropriate for your generator.

3. Low on Fuel

If you’re using propane to fuel your generator, make sure it has enough pressure in the tank. To get a good start with a generator, it’s important to have an adequate amount of pressure in the gas tank. The valves on the tank and tubing are not closed. Make sure you check the gas tank to make sure there’s enough gasoline in it. Fresh gasoline can be added when it’s necessary.

If you want to avoid hard starts, don’t use old or outdated gasoline. If the gasoline is older than two months, you should replace it with fresh gasoline. Stale gasoline can cause problems to your generator’s engine. You can refill with fresh gas by emptying the fuel tank and the carburetor.

4. Choke Lever

At startup, the choke regulates the amount of air that enters the carburetor. There could be a problem with the amount of air that mixes with your fuel during combustion if your generator isn’t starting up.

When starting a generator that hasn’t been running for at least a few hours, the choke should be all the way closed. Generator chokes’ closed position is commonly referred to as the “start” position because of this. The choke can be gradually opened to “run” when the generator warms up while it runs.

In contrast, if you recently ran your generator and only briefly shut it off, the engine will still be warm. To re-start the generator in this situation, the choke must be opened halfway to entirely.

5. Check the Air Filter

If adjusting the choke didn’t solve the problem, it may be because your air filter is to blame. If the air filter is not clean, you won’t get enough air. The air filter needs to be cleaned or replaced in order for the necessary amount of air to enter the carburetor. If you open the air filter housing on the side of the generator, you can check the air filter element. It is necessary to clean or replace as necessary.

6. Bad Spark Plug

Spark plugs can accumulate deposits and buildup over time. Remove the spark plug and look for deposits with the spark plug.  Use a tiny knife or similar instrument to clean the spark plug if necessary. Make sure the spacing between the electrodes is correct (To determine the required gap for your model, consult the specifications page of your manual.). If you want to check the plug, pull on the recoil starter while holding the body of the spark plug against the crankcase of your generator. The ignition coil is in good working order if the sparks are bright and blue in color.

The spark plug and cap should be removed if there is no spark or the spark seems to be faint. You may examine your engine’s ignition coil by securing a spark plug wire near the body and then pulling the recoil starter. Replace the spark plug if sparks are now visible between the plug boot and the engine. Replace the spark plug. A new ignition coil may be necessary if no sparks.

7. Clogged Carburetor 

After a long period of storage, there’s a good chance that your generator’s carburetor is clogged by old gasoline. To remove this gasoline, you need to close off the fuel valve and open the carburetor drain. You can also remove the entire carburetor from the bottom of the generator and clean out any old gasoline with a brush and towels. Once you’re sure it’s free of gasoline, you can clean the brass jet nozzle on your generator’s carburetor using a sewing needle or safety pin.

Also, it’s unwise to store your generator for extended periods of time without draining its gas tank first.

8. Low Oil Sensor Malfunction

The low oil sensor keeps the generator from starting when the oil is low. When running on an uneven surface, the low oil sensor might misread the oil level and cause your generator to start. If your generator start after disconnecting the low oil sensor, it’s likely that’s the problem. Don’t try to cover up a low oil sensor problem by disconnecting the low oil sensor indefinitely. Running your generator at low oil levels can severely damage your engine.

9. Clogged Fuel Valve

Leaving fuel in your carburetor or gas tank prior to storage may cause the fuel valve to become clogged, in addition to the carburetor becoming clogged. The first step is to ensure that the fuel valve is open, and that if your generator has a vacuum relief valve located above the gas tank, that it is also opened.

Unplug the hose from the intake side of the fuel valve to see if gas can flow freely through the line. If it does, use a container to catch any spilled fuel as you do this. A smart suggestion is to remove the in-line fuel filter and physically inspect it for obstructions if your generator has one.

10. Something Plugged In

Having cords hooked into your generator’s outlets can also hinder it from starting, but this is a simple problem to fix. Even extension cords that don’t have appliances connected at the other end should not be plugged into the generator when it is being started.

11. Flywheel Key

The flywheel key is part of the flywheel. It attaches to the crankshaft and engages with the flywheel. The flywheel key may break if the generator engine stops suddenly. Remove the flywheel from the engine and inspect the key to determine if it is broken. The key for the flywheel should be replaced if it is broken.

Other Preventive Measures

Preventive maintenance can keep your equipment in good shape, which helps avoid big and expensive repairs down the road. Following a few simple tips can make it easier to prevent problems from arising.

  • To avoid hassle at the time of problems, always keep a spare stock of spark plug, fresh gasoline and ignition coil.
  • You should empty the carburetor before you store your generator.  
  • Run your generator for half an hour every month to test its reliability.
  • Make sure your generator is kept away from rain and dirt, and always store it in a covered area. It’s also a good idea to store it in a shed if you have one.
  • You shouldn’t let gas sit in your tank for more than a couple of weeks.
  • Generators need to be serviced regularly. This helps to keep your generator’s engine and other parts lubricated, free from rust, and it will help to extend the life of your generator.
  • Oil filters, air filters should be changed at regular intervals.
  • It’s a good idea to check the cooling system of your generator after few weeks.

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I am a mechanical engineer with years of experience working on Internal combustion engine and fixing electrical and mechanical systems, generators, transfer switches, and equipment related to storm water and sewage pumping stations.