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Your Generac Generator Starts Then Dies (12 REASONS)

You’re without power and now your generator won’t stay running. Check out my list of common problems that can keep a generator from running.

A Generac generator starts and then dies due to an empty fuel tank, plugged fuel filter, dirty carburetor, clogged fuel line, bad gas cap, dirty spark plug, faulty ignition coil, low engine oil level, or old gas.

Wait for the engine to cool and remove the spark plug wire before performing any repairs. Follow the safety precautions found in the Generac operator’s manual.

Genera generator starts and then dies

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Follow all safety instructions provided in your equipment operator’s manual prior to diagnosing, repairing, or operating. Consult a professional if you don’t have the skills, or knowledge or are not in the condition to perform the repair safely.

12 Reasons Your Generac Generator Starts Then Dies

Gas Tank is Empty on a Generac Generator

You know your Generac generator won’t run without gas. This is common knowledge. I only mention it because, sometimes out of frustration, you forget to check this obvious reason.

SOLUTION: Add fresh fuel to the generator when it is running low or is out of fuel.

Old Fuel in a Generac Generator

Gas sitting in a generator for a long period can leave behind a varnish that gums the fuel system and causes fuel restrictions. When less fuel is getting to the engine, the generator will sputter and possibly die.

Because gas begins to break down as soon as 30 days after you purchase it, it’s important to run fresh gas and consume it within 30 days.

I know this is easier said than done. You may only use the generator during a power outage and you never know how long that will be.

This is why you should add a fuel additive to fresh gas before you add it to the fuel tank. A fuel additive like Sea Foam Motor Treatment will stabilize fuel and reduce moisture so it lasts a little longer.

Follow these tips to get the best fuel results:

  • 4-cycle generators require unleaded gasoline with a minimum 87 octane rating and a maximum ethanol content of 10%. Don’t use gasoline with higher ethanol contents.
  • Use gas within 30 days.
  • Don’t leave gas outdoors where it can attract moisture.
  • Store gas in a dry place.
  • Only buy enough gas you can use within 30 days. If you purchase more than this, add a fuel additive to stabilize your gas.

SOLUTION: Drain old gas into a container to be disposed of properly. Add fresh fuel with a fuel additive to stabilize and clean the fuel system.

Plugged Fuel Filter on a Generac Generator

Generac portable fuel filters use an inline fuel filter inserted between the fuel lines to strain fuel before it gets to the carburetor. Its purpose is to keep dirt and other debris from passing through the fuel system.

Dirt trapped by the filter can build up keeping fuel from flowing through the filter. The engine may die because it isn’t getting sufficient fuel.

SOLUTION: Replace a dirty fuel filter.

Fuel Line Blockage on Your Generac Generator

Another thing that can restrict fuel flow is a clogged fuel line. To find a clog in a fuel line, stop and start the fuel flow while checking the fuel flow coming from each section of the fuel line.

SOLUTION: To remove a restriction from the line, remove the fuel line from the generator and spray some carburetor cleaner into the line to help loosen the clog. Next, blow air through the line using compressed air until the clog is removed.

Reinstall the line. If you can’t get the clog removed or you find your fuel lines are dry and cracked, you can easily replace it with a new fuel line purchased from your local hardware store.  

Bad Fuel Pump on Your Generac Generator

Your Generac generator will use a fuel pump when the carburetor sits higher than the fuel tank. It requires a pump to move fuel uphill.

When a fuel pump fails to work, the carburetor won’t get enough gas and the generator will die.

Before you begin testing the fuel pump, confirm you are getting fuel to the inlet port on the pump. Then remove the line from the carburetor and place it in a container. Start the engine and watch for a steady or pulsating flow coming out of the line.

SOLUTION: Replace a fuel pump that is unable to provide a constant flow of fuel to the carburetor.

Dirty Carburetor on Your Generac Generator

A dirty carburetor may gum up and prevent the carburetor from allowing the right amount of gas and air needed to create a combustion in your engine’s cylinder. The Generac generator may run sluggish and shut down when the engine is no longer able to get the air and fuel it requires.

SOLUTION: Clean your carburetor to remove gummy deposits and crusty buildups that remain from running old fuel and fuels with ethanol. If your carburetor is excessively dirty or has broken components, you may have to rebuild or replace it.

Wrong Choke Setting on a Generac Generator

A Generac generator with a cold engine must be started with the choke closed to restrict air. Once the engine warms up the choke must be adjusted to the open position to allow more airflow so the engine continues to run.

SOLUTION: If your engine starts and then shuts down right away, you need to make sure the choke is off and in the open position.

Clogged Air Filter on Your Generac Generator

The air filter is essential to keep dirt from entering the air intake allowing dirt to wear the engine. This is an important part that must be routinely checked to keep it in good condition.

For the average homeowner, I recommend replacing the air filter annually and cleaning it a few times a year. When you notice the filter is extremely dirty or damaged, you must replace it.

You will definitely need to replace it more often if you are running the generator in dry dusty conditions.

If you are not cleaning and replacing the filter regularly, the filter can become plugged with so much dirt that the engine won’t get sufficient air. It can overheat and cause extensive permanent engine damage.

SOLUTION: If you find your air filter is plugged, clean it using the procedure below for your type of air filter. If you are unsure of the type of filter you have and its cleaning procedure, consult the Generac operator’s manual.

Clean a Generac generator foam-style air filter

  • Remove the air filter from the housing.
  • Wipe out any dirt remaining in the air filter housing and cover. Don’t allow dirt to fall into the air intake.
  • Inspect the foam filter for damage and replace it if needed.
  • If the filter is in good condition, clean it in soapy water and rinse it until the water runs clear.
  • Squeeze the filter and allow it to dry.
  • Install the air filter.
  • Reattach the air filter cover.

Clean a Generac generator paper air filter:

  • Remove the air filter from the housing.
  • Wipe out any dirt remaining in the air filter housing and cover. Don’t allow dirt to fall into the air intake.
  • Inspect the paper air filter. Tap the filter to loosen dirt so it falls from the filter. If the filter is very dirty, damaged, or no longer seals the air intake sufficiently, replace it with a new one.
  • Install the air filter.
  • Reattach the air filter cover.

Bad Gas Cap / Fuel Tank Vent on Your Generac Generator

The fuel tank needs to have a vent so air is able to pass through it to equalize the pressure in the fuel tank. When the vent is plugged, the tank will form a vacuum and won’t allow fuel to get to the carburetor. This will keep the generator from running.

You can determine whether the fuel tank vent is your problem by loosening the fuel cap and starting the generator. If the generator runs well, try to replicate the issue by retightening the fuel cap.

Allow the generator to continue to run to see if it begins to run sluggishly and shuts down. You most likely have a problem with the fuel tank vent if it does.

The fuel tank vent may be built into the gas cap. It may also be an independent vent installed on the top of the fuel tank.

SOLUTION: Replace the gas cap or rollover valve tank vent (depending on your model Generac) when you find the fuel tank is no longer venting properly.

Dirty Spark Plug on Your Generac Generator

The spark plug provided the spark required to get it started, however, if the plug is very dirty or damaged, it may have intermittent spark problems that will cause the generator to sputter and die.

SOLUTION: Remove the spark plug and check its condition. If the tip is very dark in color, the electrode is worn or the porcelain is broken, you must replace the spark plug with a new one.

If it appears in good condition, clean it with a wire brush and check the electrode gap and securely attach the spark plug wire. A loose wire or incorrect spark plug gap can also cause the generator to quit running.

Bad Ignition Coil on Your Generac Generator

Before checking for a bad ignition coil, make sure your spark plug is in good condition. The ignition coil provides voltage to the spark plug so it can start the engine.

If the spark plug isn’t able to fire due to a bad spark plug or ignition coil, the engine will not start.

SOLUTION: Check the continuity of the ignition coil using an ohm meter. If you find a break in the continuity, replace the ignition coil.

Insufficient Engine Oil Level in Your Generac Generator

Your generator may be running for a while and then suddenly stop. Check to see if the low engine oil light is on. When the oil level is low, Generac has a sensor that will shut it down to protect the engine from damage. It will not restart until the engine oil level is corrected.

It may be frustrating that it won’t keep running. However, the generator shutting down is a good thing.

Continuing to run an engine that is low on oil can result in significant engine damage because a lack of sufficient lubrication will cause friction to build in the engine. The engine can become so hot that the parts can begin to melt.

SOLUTION: To check the engine oil level, begin by placing the generator on a flat-level surface. Remove the oil fill cap and wipe off the dipstick with a clean cloth to remove the oil.

Reinsert the dipstick into the oil-fill tube, but don’t screw on the cap. Remove it and look at the oil level on the dipstick. Ensure it is in the full range on the dipstick.

If it is not, correct the engine oil level by removing or adding a little oil until it is at the correct level. When you find you have the correct engine oil level and the low oil sensor stays on, you may have a faulty sensor. It’s best to take the generator to a service center to be repaired.