Generator Care Generator Troubleshoot

Why Does My Generator Keep Stalling

Generator Keep Stalling

Generators are crucial equipment to have at your home. It comes quite in handy during a power emergency. However, sometimes, it does experience issues that can quickly get to your nerves, one of them is stalling. So, why does your generator keep stalling?

There is no one answer to this question. A generator can stall when running on bad fuel, and if the spark plug is faulty, using a clogged air filter or dirty carburetor, the chock valve is stuck closed, the float needle valve leaks, or when the oil sensor is faulty. All these issues are possible culprits if a generator stalls.

This post will explain how each of the problems can cause the generator to stall and troubleshoot them. Let’s jump right in!

What Might Be Causing a Generator to Keep Stalling?

If you’re trying to start your generator, it starts but dies after seconds or minutes; then your unit is stalling. Usually, this would happen when you try to start the engine with low fuel in the tank. But I’m assuming that isn’t the case with yours. Right?

If you have enough fuel in the fuel tank but the generator is starting and then shutting down almost instantly, here are possible reasons and how you can solve them.

1. Bad Fuel

Gasoline is a hydrocarbon that, by itself, doesn’t go bad. When gasoline sits for long periods, it may go bad. The fuel has water in it, or other contaminants cause issues if not used right away. A bad batch will cause the generator to stall and run very poorly until all the old gas is purged out by running new fuel through the system.

Unlike other fuel types, gasoline comes mixed with ethanol and other additives. When ethanol is exposed to air, it attracts moisture that contaminates the fuel. Usually, this happens when you store the gasoline in a fuel container not designed for storing fuel or in your generator.

Stale fuel is another way you can experience bad fuel. It happens when the additives used in gasoline evaporates, leaving unusable fuel but enough to start the generator but not keep it running. Today, gasoline goes stale as early as 30 days. Even if you add the fuel stabilizer, at some point, the fuel will go bad.

Usually, if you use bad fuel, the generator might start, and as it continues to run, bog down and stall.

Pro tip: label the fuel in your storage from the days you acquired it if you want to stay ready for an emergency.

2. Bad Spark Plug

Another possible culprit for your generator stalling is a bad spark plug. It’s rare for a spark plug to go bad, but it’s also possible. At times the gap might have expanded, or the terminals might be covered with carbon residue. Either of this can make the spark produce weak to no sparks needed to ignite the fuel mixture in the combustion chamber.

Combustion requires continuous production of these sparks to keep the engine running. A dirty spark plug can produce enough spark to start the generator but fails to make enough for the next cycle. The same happens if the gap is too wide.

Start by cleaning the terminals with a soft wire brush to get rid of the carbon deposits. Return it and try to start the generator. If the generator attempts to start but fails, get a gapping tool, adjust the gap, and test it again. If nothing improves, it’d be best to replace it.

3. Clogged Air Filter

If it’s been ages since you last changed your air filter that might be another common cause of generator stalling. It’s there to make sure no contaminants reach the carburetor. This keeps your generator running safely, efficiently, and powerfully for years of reliable use.

However, the accumulation of dirt and debris on the filter cartridge or form would reduce the amount of air reaching the carburetor. That means the engine will be running reach. The generator engine will start but won’t stay running. It will run for seconds or few minutes before stalling and dying.

You want to remove the air filter foam or cartridge to clean it. If too dirty, consider replacing it. It’s recommended that you change or replace an exhausted filter with a new one every 12 months or every 100 hours of usage, whichever comes first.

Pro tip: It’s important to remember when replacing filters in generators, make sure they are compatible with the unit model number – do not assume!

4. Choke Valve Stuck

The gas-air mix ratio has to stay optimal for fuel combustion in the engine to take place properly. When the choke valve is stuck closed, enough air will be mixed with gasoline in the carburetor. That would mean the generator will be running rich, leading to incomplete combustion.

Usually, the generator will start, but during the first few cycles, unburnt fuel. The accumulation of these burn fuels will flood the engine and cause the generator to stall.

The most common cause of stuck chock valve is varnish made when gasoline goes stale as its additives evaporate. So, you can solve the problem by cleaning it with a carburetor cleaner.

5. Clogged Carburetor

Before gasoline reaches the generator engine, it goes through a carburetor where it’s mixed with air in the right ratio to allow proper burning for ideal power production. The carburetor has two fuel jets and a series of passageways used to regulate the fuel passing through to the combustion chamber.

If debris finds its way into the carburetor, it can block the passageways and cause the generator to run lean. The amount of gas reaching the fuel will be lower, and the air to fuel ratio won’t be optimized. When the right conditions are met, the generator will stall. You might start with problems getting the engine running, and when you do, it doesn’t take long to shut down.

The same would happen if you left the generator with untreated gasoline for more than a month or more than six months with treated one. Some of the gasoline additives evaporate, leaving gum/resin-like stuff behind called varnish. If you store your generator with fuel in the carburetor, the varnish can clog the passageways and restricting the amount of fuel reaching the engine.

If this is the case, you want to disassemble the carburetor, take it apart and give it a thorough cleaning. Take a picture before you remove it so that you can have an easier reassembly.

Here is a complete guide on how to clean a carburetor.

6. Float Needle Valve Leaking

If your generator is still stalling, there is a chance the float needle valve in the generator carburetor is leaking. It’s a common problem that can cause the generator to stall or even not start. Mostly, this issue would flood the combustion chamber preventing proper compression. Normally, the generator might start during the first pull and stall when the chamber receives too much fuel.

When fuel enters the carburetor, it fills the bowl, and the float controls its needle valve when it moves up. If the float’s positioning was wrong or something was preventing the needle valve from sealing right, the combustion chamber would flood.

The most common symptom of a flooded engine is gasoline in the crankcase. Open the dip, check the oil level. If it’s overfull, there’s a chance it’s the gasoline that filled it. Try smelling it. If you get a gasoline smell, there’s a problem with your float needle valve.

Normally, I wouldn’t advise you to troubleshoot this problem, but if you’re DIYer and you enjoy doing stuff like this, you can rectify it yourself.

The first step would be to disassemble the carburetor, set it on a table and give it a thorough cleaning.

After putting it together, hold it vertically with the float bowl out and the float facing down. You want to make sure the floating head is horizontally parallel with the float bowl line.

If it’s slightly out, your generator engine is running lean, and if slightly in, it’s running rich. Use the small metal clip on the side to adjust the position by gently pushing it in and out.

7. Faulty Low Oil Sensor

The oil sensor is a safety feature installed inside the engine crankcase to prevent it from running with low oil. Normally, its float sits on the oil inside the crankcase; when the level reduces past the recommended level, the sensor switches off the engine.

If it were to malfunction and sense a low oil level, the same would happen. The generator can start as normal, but it stalls once it starts running and the oil sensor multifunction.

To troubleshoot a faulty low oil sensor, you need to locate the two wires running through to the inside of the crankcase. Usually, they are green and yellow. One of these two wires will have a quick connection. Disconnect it and try running the generator again. If it doesn’t stall, congrats, you have found the problem.

However, fixing such a problem is highly expensive as it requires taking the engine apart to reach the oil sensor float, and there is no guarantee it will work again. So, a better, though the less risky, option is to bypass the oil sensor by leaving it disconnected.

However, you will want to have a way to make sure you add or check the oil before starting the generator. As running it without oil is dangerous and can lead to catastrophic engine failure.

Related Questions

Does a spark plug fire continuously?

Yes, of course. The spark plug produces sparks that ignite the fuel and cause an explosion inside the combustion chamber. It’s supposed to keep making the sparks to keep the engine running. If it were to stop, then the engine would stall.

About the author

Sharif Gen

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