How to Start a Car With a Flooded Engine

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It is necessary to know how to start a car with a flooded engine since car engine flooding is a common cause of car breakdowns, especially on cool or colder days. 

That’s why our car maintenance and repair professionals are here to guide you on how to react and what the proper course of action is needed to start a car with a flooded engine – whether that is calling your mechanic or taking care of it yourself.

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When your car’s engine becomes flooded with fuel, the spark plugs become wet and the necessary spark to ignite the air/fuel mixture is shorted to ground instead of jumping the spark plug gap and igniting the mixture. 

This situation is much more common with older vehicles that employ a carburetor but can still happen on more modern, fuel-injected cars as well. In the event that it does, it is important to understand the basics on how to start a car with a flooded engine.

What Does It Mean When Engines Become Flooded?

A flooded engine happens when too much fuel enters into the combustion chamber, hence the term “flooding”. A flooded engine has too much gas and not enough oxygen. This wets the ends of the spark plugs, and they won’t ignite the fuel. 

A gas engine floods with fuel when it’s switched off too soon after being started from cold. After switching off, the unburned fuel remains in the engine and wets the spark plugs, which prevents ignition and makes the car difficult to restart. It is also possible for an engine to stall from a running state due to this condition.

An internal combustion engine needs three things to properly function: air, fuel, and spark. A carefully mixed combination of air and fuel is placed into the combustion chamber of an engine and ignited by a spark plug. 

On carbureted motors, the air/fuel mixture is completed in the carburetor itself and then let into the combustion chamber via intake valves. On a fuel-injected motor, the air-fuel mixing process takes place in the combustion chamber itself. 

How Can I Tell If My Engine is Flooded?

There are a few signs that will let you know that you have too much fuel in the engine:

  • Trouble starting: Your car might have trouble starting up if the engine has excess fuel. In colder weather, this problem may arise since it takes more fuel to start the engine. 

The engine cranks excessively quickly and makes a strange “whirring” noise while it does so. The car doesn’t start or starts briefly and cuts out again

  • Smelling gas: A strong smell of gas, especially around the exhaust could be a sign of a flooded engine.
  • Emission color: Another indicator is dark smoke from your vehicle’s exhaust system. If it is a darker smoke, this could also be a sign that your engine is flooded.
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The symptoms of a flooded engine are very similar to other issues with your vehicle’s engine or electrical system. A blown starter, bad battery, clogged injectors or even a vacuum leak could cause an engine to struggle to start up. 

The real difference is the presence of black or sooty smoke coming from the tailpipe and the smell of gasoline, which is unique to a flooded or soon to be flooded engine. If you see these tell-tale signs, don’t make anymore attempts to start your car — it may make things worse.

How Does Your Engine Get Flooded?

Flooding the engine has nothing to do with water but the amount of fuel that’s been introduced into the engine. A more common mechanical ailment for cars that employ a carburetor rather than fuel injection, a flooded engine occurs when your engine is overcome with too much fuel. 

This will typically occur when you hit the gas too hard or pump the accelerator too much when starting your car. If you’ve just started it, moved it a few yards and shut it off again, you’ve flooded the engine.

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This is really common, as we sometimes want to move a car under the carport into some shade or a better parking spot without driving it any more than a few yards.

How to Start a Flooded Engine?

Perhaps the best remedy for a flooded engine is time. Leave it sitting for a while for the fuel to evaporate. If the spark plugs aren’t too badly fouled, this can work. After about 20 minutes, try starting your car again without hitting the gas pedal. 

This allows heat present in the engine to help vaporize the fuel in the cylinders and on the spark plugs. If this doesn’t work, there’s another technique you can try. Hold the gas pedal to the floor and repeatedly attempt to restart the engine. Do not pump the gas pedal. 

This permits the maximum flow of air through the engine, flushing the overly rich fuel mixture out of the exhaust. When the engine starts, release the gas pedal and let it run for a few minutes. 

On a fuel-injected engine, ignoring the throttle (no fuel) while starting permits electronic logic systems to produce the correct fuel mixture, which is often based on exhaust gases. 

Some fuel injection computers interpret “pumping” the throttle to indicate a flooded engine, and alter the fuel-air mixture accordingly. 

Once the engine’s started, allow it to rev up for a second or two, then hold it at a higher than normal idle speed for a few more seconds. Once the engine’s warmed up, you can switch off safely or use the car normally.

In the worst cases, the excess fuel can foul spark plugs. When excess fuel floods the engine, it can soak spark plugs, making them incapable of creating enough of a spark to start the engine. You’ll want to let them dry out or replace them before attempting to start the car. 

To get the spark plugs out, you’ll need a socket set. To clean them, you’ll need some spark plug cleaner from an automotive store. 

A dirty fuel injector could also cause your engine to flood. If you find that your engine floods frequently, you may want to check your fuel injectors and run some fuel injector cleaner.

Preventing Flooding From Happening

It’s best to always allow your gas engine to warm up once it’s started from cold. This only takes a few minutes – it’s warm enough once the engine notes changes and the idle speed drops slightly. You’ll also see the temperature gauge move off the minimum.

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If you have to move your car just a few yards, let it idle for a couple of minutes before you shut it off. This will give the engine enough time to restore the air/fuel balance. 

You’ll need to feed the engine some gas to start a car with a carburetor, but the trick is to not pump the accelerator excessively prior to starting the vehicle. 

Fuel-injected motors utilize sophisticated electronics to ensure the proper amount of fuel is delivered to the cylinder at the proper time.

Can you flood a diesel engine? Diesel engines work differently than gas engines. They’re not usually at risk of being flooded with fuel.

If your engine is flooded with water rather than fuel, that’s a different problem. It could cause a lot of damage depending on how much water got in. To avoid flooding your engine with water, it’s best to drive carefully through fords and floods.

Our Car Experts Can Help You Start a Car With a Flooded Engine

Not everyone who drives a car is a mechanic, though that does not mean you can’t have an understanding of how to fix potential issues or recognize them as they occur. 

If you still are having trouble getting your engine to properly start after trying these remedies, it’s time to have a professional take a look at your vehicle.  American Auto Care can identify the problem and quickly replace parts if needed. 

So if your engine is flooded, and you’re unable to fix it yourself, schedule an appointment with us at 951-461-2507, and let our trained technicians get your car back to performing the way it should.

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