12 common reasons why your generator won’t start

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    There’s nothing more frustrating than taking your generator out of the garage only to find that the engine isn’t starting as it should. Fortunately, if your generator won’t start, it’s typically a minor inconvenience rather than an indication of a more serious issue.

    The best starting point for troubleshooting generators is some of the most common causes of starting problems.

    In this blog post, we’ll take a look at the top 12 reasons why your generator won’t start and help you fix them.

    Let’s get started.

    12 Commons reasons your generator won’t start

    The main reason why the generator won’t start are:

    1. Insufficient generator fuel

    This may seem obvious, but it’s worth checking your generator tank for gas. If not, that’s the obvious reason your engine won’t start. If you are using propane to fuel the generator, make sure the tank has enough gas and all valves on the tank and pipes are open.

    Remember that using gasoline that is stale—generally anything older than two months—can harm the engine of your generator. If there is stale gasoline in the tank, you will need to empty the tank and carburetor and refill it with fresh gasoline. Be sure to use the kit to remove any bad fuel safely.

    2. Your engine oil is low

    Oil is just as essential to the generator’s operation as its fuel. The majority of modern generators come with a sensor that, in order to safeguard the engine, when the oil level is low, automatically turns the generator off. If you haven’t had an oil change for more than 50 hours (or 20 hours in the case of a new generator) or suspect you may have a leak, low oil is most likely the cause of your generator’s starting problems.

    You can check the oil level with the oil dipstick on the generator, which may be located in the crankcase. If the oil level is low, check the manufacturer’s guide on which type of engine oil is right for your generator. While starting the generator may not be necessary, it is good maintenance practice to change the filter when you add more oil.

    3. The battery is dead

    If your generator has an electric starter, such as a push button or remote, you must first determine whether the starter’s battery is malfunctioning. Like in a car, the electric starter won’t work if the alternator’s battery runs out.

    The easiest way to fix this is to try an auxiliary recoil starter (if your generator has an auxiliary recoil starter). If feasible, you can charge the electric starter battery from the 12 volt DC outlet on the generator after the generator is running.

    You’ll need to charge the battery if you don’t have a recoil starter on your generator. You can do this using a 12-volt DC outlet in your car or a converter with a household AC outlet.

    Alternatively, you can use a jumper cable to use the car battery to start the alternator battery. The procedure is the same as starting another car’s battery:

    • Connect the cable to your car and the generator using the generator’s metal frame as the fourth connection point.
    • Turn on your car.
    • Try to start the generator.

    If none of these approaches succeed, a dead battery might not be the cause of your generator’s inability to start.

    4. The generator has cables plugged in

    Another easy-to-solve problem that can prevent a generator from starting is plugging a wire into the generator’s outlet. Whenever you start the generator, you should never plug in anything — not even an extension cord that isn’t connected to any appliances on the other end.

    5. The choke is either too open or too closed

    The choke controls the amount of air that flows into the carburetor during startup. If your generator is trying to start, but the engine doesn’t seem to be turning, the issue may be that there is too much or not enough air being mixed with the fuel during combustion.

    When starting the generator cold — that is, it hasn’t been running for at least the past few hours — the choke should be set to close completely. For this reason, the closed position is often marked as the “start” position of the generator choke. Once the generator starts to warm up while running, the choke can be gradually turned fully open or “running.”

    On the other hand, if you’ve been running the generator recently and only briefly shut it down, the engine is still hot. In this case, the choke must be fully opened halfway through to restart the generator.

    6. You should replace your air filter

    If adjusting the choke seems to help but doesn’t fix the problem, your air filter may be the culprit. If the air filter is clogged with debris and dust, your carburetor won’t get enough air to burn.

    Air filters are usually easily accessible and visually inspected. Replace it and move the choke back to the proper starting position if it appears dirty or clogged.

    In general, cleaning your generator properly can help solve your problem.

    7. Spark plug is dirty

    Dirty spark plug

    If the engine doesn’t even try to flip during startup, the problem might be your spark plugs. To check your spark plug, first, remove it from the engine using the spark plug socket. Spark plugs need to be replaced if they have deposits that cannot be removed with a brush.

    Otherwise, remove any debris from the spark plug and adjust the electrode gap according to the specifications in the owner’s manual. If your generator has a recoil starter, you can double-check that the spark plug is working by leaning it against the engine crankcase while pulling on the recoil starter – a working spark plug will produce a blue spark. If all is well, replace the spark plug in the engine and try starting the alternator again.

    8. Carburetor clogged

    If you didn’t drain the carburetor before you stored the generator for a month or more, this might be the culprit behind your starting problems now. Old gasoline can create blockages in the carburetor that keep new fuel from getting through.

    To clean the carburetor:

    1. Remove the bowl from the bottom of the carburetor and shut the fuel valve.
    2. Use a brush and towel to remove any fuel debris, and use a sewing needle or safety pin to remove dirt from the brass nozzle.
    3. Remember to reopen the fuel valve before trying to start the generator again.

    9. Ignition Coil

    When the engine is running, the ignition coil sends voltage to the spark plugs. If the ignition coil is faulty, the engine may not start. Before replacing the ignition coil, make sure the spark plug is working properly. If you have confirmed that the spark plug is working properly, test the ignition coil with an ignition coil tester. If the ignition coil is faulty, replace it.

    10. The fuel valve or pipeline is blocked

    In addition to the carburetor, the fuel valve may be clogged if you leave fuel in the carburetor or tank before storage. Make sure the fuel valve is open first. The vacuum relief valve on your generator will also open if it is located above the fuel tank.

    If this still doesn’t work, you can unplug the hose from the inlet side of the fuel valve to check that gasoline is able to flow freely through your fuel line – make sure you have a handy bucket to collect any flowing fuel for this. It’s a good idea to remove the in-line filter from your generator and visually inspect it for obstructions if there is one there between the fuel valve and the carburetor.

    11. Low oil level sensor failure

    The low oil sensor is designed to prevent your generator from starting when the oil level is low – but if it fails, it can prevent your generator from starting no matter how much oil you have. Keep in mind that running the generator on an uneven surface will cause the low oil sensor to misread the oil level, so simply leveling the generator will fix this.

    To check if the low oil level sensor is the cause of your starting failure, disconnect the sensor by unplugging the wire coming out of the engine crankcase. If the generator starts after being disconnected, the low oil sensor is likely to be the culprit. Usually, if the sensor is plugged in again after the generator has been running for a few minutes, the sensor will work, but if it fails, the sensor needs to be replaced, which can be a time-consuming task that requires taking your engine apart.

    Never remove the low oil level sensor to mask a low oil level problem. Running the generator with low oil levels can severely damage the engine and cause significant danger. Before disconnecting the low oil level sensor, make sure your oil is full, and your oil filter is not clogged.

    12. Check the safety switch and on-off switch

    You can check the safety and on-off switch with a multimeter to determine if it is defective.

    Proper care and maintenance can avoid these problems

    Most of the generator-starting problems listed in this blog post can be avoided with proper care and maintenance. It would be best if you had your generator serviced by an authorized agent according to the maintenance schedule in the owner’s manual.

    If you choose to service the generator yourself, always use the specified grade of oil and the correct filter in the engine.

    Periodically perform a visual inspection of the generator. Replacing worn or damaged pipes and wires before they become a problem will save you a lot of trouble.

    Drain the carburetor and empty the fuel tank before storing the generator for 3 months or more. To drain the carburetor, you simply switch the fuel tap to the off position while the engine is running. It will go on for a while, and then the engine will stop from lack of fuel. This means that there is no residual fuel in the carburetor that can cause blockages later.

    Final words

    Remember, this is a general overview of generators of all styles, shapes, and sizes. Please refer to the manual for your specific generator model for a more specific breakdown of recommended startup and troubleshooting guidelines.

    If you’re still having trouble starting your generator, feel free to give us a call at (+86) 17380831819 to speak with one of BISON’s friendly and knowledgeable technical support personnel or contact us online.

    generator won’t start FAQ

    Battery failure is the most common generator problem. Batteries wear out over time, providing less and less power over time. Knowing the lifespan of a generator battery will ensure you know to replace it before it stops working.

    If the fuel tank is overfilled, fuel can spill onto a hot engine and cause a fire or explosion. Do not fill up the gas tank. Always leave room for fuel expansion. Never add fuel while the unit is hot or running.

    The spark plugs should be removed in order to determine whether your engine is full of gas. If it’s wet, it’s flooded, and you need to let the cylinder dry out before trying to restart it. Compressed air can help the process speed up.

    Yes, generator carburetors can be cleaned without disassembly if not completely clogged. You can spray carb cleaner directly inside the carburetor or add a fuel conditioner to the tank to get rid of all the debris and dirt.

    Utilizing the power switch, shut off and restart the generator. This action should reset the overload button. After that, you need to look for the standard button for circuit protection and reset it by pressing it. After doing this, you must press the overload reset button.

    If your portable generator is running but not generating power, it may have blown a fuse or tripped a circuit breaker. Resetting the breaker and replacing blown fuses will easily solve this.


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