5 Common Signs And Symptoms Of Bad Fuel

Everybody wants their car to run smoothly but imagine you are driving your car and suddenly it stops. And now you are having a hard time starting it. Are you sure it won’t ruin your mood? You may face this situation if your car’s filled with bad fuel. Bad or contaminated fuel can make your engine suffer and your car may stall. There are some ways in which your fuel gets contaminated. Also, your car may get filled with bad fuel without you knowing that.

Fuel is always refined before its supplied but gets contaminated when stored or transferred. Fuel needs to be refined and clean for an engine to work properly. The engine’s performance depends on fuel. Your car’s fuel gets bad if it’s stored for years and this can also damage your fuel tank. Fuel’s quality can not be compromised as your car’s and engine’s performance depend on it. So there are some signs and symptoms of bad fuel inside gas tank that you need to check out.

Common Causes Of Contamination Of Fuel:

There are many ways in which your fuel may get contaminated. After leaving refineries, fuel is stored or transferred and contaminants get mixed in fuel meanwhile.

  • Your fuel gets bad if you leave your vehicle unused for months or years, i.e. fuel gets bad when is stored for years in the same fuel tank.
  • Water gets mixed with the fuel at the gas station because of a damaged water filter in their pump.
  • If you live in a cold place, water may get mixed with fuel in your gas tank because of condensation.
  • Fuel may get contaminated if your car’s fuel tank has dirt settled down in it.
  • Also, your gas tank can develop contamination due to water, rust, corrosion, condensation, and microbial growth.
  • Corrosion around injector inlet.
  • Fuel may get contaminated while a tanker delivers fuel to the customer.
  • Fuel flows through pipelines, and if there’s dirt, corrosion, or rust in pipelines, fuel will pick all of it on its way through pipelines.
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Signs And Symptoms Of Bad Fuel:

You won’t know if your vehicle is filled with contaminated or bad fuel. But you can watch out for some signs indicating bad or contaminated fuel. So here are some symptoms of bad fuel inside car:

1. Trouble Starting Engine:

Bad fuel is one of the reasons why your vehicle has trouble starting. Although it’s still a problem but is better than any other like bad spark plugs or a dead battery as these problems are more costly to fix. If there is any issue with the fuel system, a check engine light appears. Every car owner is aware of this light. You can find the problem with an OBD2 scanner as it allows you to read error codes or if you don’t have any diagnostic scanner, you can take your vehicle to an auto shop.

2. Engine Misfiring Or Backfiring:

Your engine misfires, if there’s any problem with one of your car’s combustion chambers, or because of a faulty ignition coil, bad camshaft sensor, or worn spark plugs. However, when your fuel passes through the fuel filter and the fuel injector somehow gets disrupted, this can also cause your engine to misfire.

Your engine backfires, if the spark under the chamber doesn’t burn all the fuel, and that unburnt fuel ignites in the exhaust system. Sometimes even a flame can be seen when your car backfires. Also, backfires can actually cause damage to your engine and can cause power loss too.

3. Abnormal Speed Changes:

Bad fuel can cause a sudden change of speed when you are driving. Even if your foot is pushing the gas pedal or not, you may still notice that speed is changing for no reason whatsoever. This also indicates that you have bad fuel filled up in your car.

4. Damaged Fuel Filter:

The fuel filter is supposed to stop all the dirt and debris from making their way into the fuel tank and get mixed with the fuel. So if your fuel filter is damaged, fuel will get contaminated or will become bad. Check your fuel filter often as this can cause damage to your car’s engine.

5. Engine Stalls:

Engine stalls when there is a lack of power or fuel so if your engine is not getting enough amount of fuel it will stall. As there is fuel in fuel lines your engine may crank up just fine but will stall because enough fuel is not making its way through. The engine needs more fuel to process internal combustion to generate the necessary power. But if fuel is bad or contaminated, the combustion process won’t be able to generate enough power.

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How To Get Rid Of Bad Fuel?

It doesn’t matter if your fuel tank is full, if fuel is bad it will still cause troubles. Here’s what you should do if there’s bad fuel filled in your gas tank:

  1. Remove the tank cap and drain all the fuel.
  2. For draining the fuel, use a hose and put one end in the tank and the other end in an empty container. Suck gently at one end before putting it in the gas tank so that there will be enough pressure to drain the fuel.
  3. Now simply put some dry gasoline in the fuel tank as dry gasoline will absorb water without affecting the engine.
  4. Now fill your gas tank with high octane gas and then put an octane booster. Doing this 3-4 times, again and again, will reduce the bad fuel.
  5. Refill your gas tank with good fuel.

This may sound expensive but if bad fuel causes any harm to your engine, it will be much more expensive. And you wouldn’t want that. Also, this process is complicated so it may be better if you contact some professional mechanic and let him handle this.

How To Avoid Bad Fuel?

  • Don’t get petrol mixed with diesel if your car has a diesel engine.
  • Do not use very old stored fuel as it may be contaminated.
  • If you get filled your car with bad fuel from a gas station, try some other gas station.
  • Always buy fuel from a trusted and reputable gas station.
  • Also check your fuel filter often, if it’s damaged replace it if needed.


As bad or contaminated fuel can cause damage to your vehicle, if you encounter any of the above symptoms of bad fuel, try not to drive your car until you replace bad fuel with new clean fuel. Bad fuel can cause your engine to suddenly stop or sudden speed changes may occur, which is really dangerous. So take your vehicle to a repair shop if possible or contact a mechanic. Try not to drive with bad fuel as it can cause damage to your engine.

Thank you.

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