5 Symptoms of Bad Gas in Your Car

(Updated on June 3, 2020)

Fuel for vehicles, whether gasoline or diesel, is refined specifically for the purpose of operating a vehicle’s engine. There cannot be any contamination of the fuel whatsoever or else the engine’s performance will suffer as a result.

Contamination could mean virtually any outside substance that does not belong in the fuel, such as water. Out of all the reasons for fuel to go bad, the number one reason that car owners experience is water getting into their gas tank and contaminating their fuel.

There are a few reasons to explain how water gets mixed in with fuel, with condensation being the top reason. If you live in a cold environment, then it is common for condensation to occur inside the gas tank.

Also, there could be water in the gas pump when you fill up your tank at the gas station. Sometimes a gas station may have a damaged water filter in their pump which does not do a good job of filtering out the water from their fuel.

There is nothing you can do to prevent this obviously because it is the gas station’s responsibility. Aside from water, fuel can go bad by simply leaving it unused for months and years at a time too.

Top 5 Signs of Bad Fuel In Your Gas Tank

signs of bad gasoline

If you are unsure whether your fuel has gone bad, there are at least five signs that you can watch out for to see if this is the case. These signs are clear indicators that your fuel is either contaminated or just really old.

In most cases, you will need to have all the fuel drained from your gas tank and then replaced with fresh uncontaminated fuel. That is often the only way to remedy this situation.

If there is only a small amount bad or old gas in the tank, you may be okay by simply filling up with good quality fuel, preferably high octane, so the effects of the bad gasoline is lessened.

1) Acceleration Issues

car won't accelerate

If you step on the gas pedal and do not accelerate right away, then you are experiencing hesitation from the engine. This hesitation could be the result of bad fuel in the internal combustion chamber.

It will either take your vehicle a few seconds to respond to the gas pedal before it accelerates, or it won’t accelerate at all. The faster you try to go, the more apparent this symptom will be.

2) Abnormal Speed Changes

car speedometer

Aside from issues accelerating, bad fuel can also cause spontaneous changes to the speed that you are driving. Even if you barely have your foot on the gas pedal or not at all, you may notice that your driving speed will change drastically for no apparent reason.

This is another indicator that you have bad fuel in your gas tank and cylinder.

3) Damaged Fuel Filter

bad fuel filter

The fuel filter is responsible for ensuring that dirt and debris do not make their way into the gas tank and mix with the fuel. This could cause devastating results for the performance of your engine.

So, if you have a damaged fuel filter, this would explain why your fuel has gone bad. Periodically check your fuel filter to ensure that it is in good condition.

4) Engine Stops Running

engine stall

You may be driving along and then your engine will suddenly stop running. This can happen when you have bad fuel because the internal combustion process will not be able to generate the necessary power to sustain the demands placed on the engine.

This will cause the engine to stop running as a result.

5) Trouble Starting Engine

trouble starting car

If you have an excessive amount of water or other contaminants mixed with your fuel, then you will have difficulties with starting your engine. There could be numerous reasons for experiencing trouble like this.

But if you have experienced any of the other symptoms, then you can attribute it to bad fuel.

8 thoughts on “5 Symptoms of Bad Gas in Your Car”

  1. I have a 2020 Chevy Impala, & I think I have bad gas…my check engine light came on, I left my car on to walk in the house &came bk out and it had cut itself off…it rides a little rough…And I only have 62,000 miles on it…

    • If the tank is low, fill it with good gas. The good stuff should dilute the bad stuff enough to run properly. If the tank is almost full and you think the gas is bad, it may be worth draining the tank first.

  2. My car was starting up and running fine until I got gas yesterday. My car is a 2014 Volkswagen Beetle and within two hours my car started hesitating to start.

  3. I have a 2012 Chevy Malibu. I’ve been having difficulty accelerating for over a month and thought it was my pedal or throttle body. I was waiting to get it looked at until I got the money. However, I was driving one day and all of a sudden my car engine just shut off on me and I was stopped in the middle of the road. I had every single thing on this list happen to me. I had to get my car towed to the dealership and they told me it was from contaminted fuel. I have no idea how it happened, but if you suspect it don’t let it get worse unitl your car won’t even start. This list is very accurate.


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