Last Updated: 29.03.2022

Sugar destroys a gas engine – is it a fact or fiction? 

For a long time now, there are persistent rumors and endless debates about how sugar can ruin a gas tank. For whatever reason that sugar finds its way into the tank—it could be that someone has a grudge on you or pulling a bad prank—should you be worried? What should you do? 

What does sugar in a gas tank do? Read on as we bust some myths and share some facts to make you well-informed! 

What Does Sugar in a Gas Tank Do?

man pouring sugar in a gas tank

One of the most common urban legends about cars is that putting sugar in a gas tank will kill the engine. From movies to songs, there are many references in pop culture that support such a notion. It might turn gooey and will caramelize, creating nasty deposits and gunk that negatively impact the fuel system. Is this true? 

Apparently, it isn’t as damaging as many people assume. 

When sugar gets in the gas tank, it does not dissolve in the same way that it would in water. Instead, it will settle at the bottom of the tank. This way, it won’t kill the engine or cause the latter to blow up. Nonetheless, it does not mean that it won’t cause any problems. 

So, the assertion that sugar kills an engine is pure fiction. However, it is a fact that it can cause less serious problems. 

How It Started

sugar on wooden table

The premise that sugar kills a gas engine has been around for decades. It was popular in the 1950s when a lot of people would report that someone added sugar to their tank. As a result, they cannot start their engine and suffer from various performance problems. 

The vehicles in the 1950s are very much different from what we have now. A common feature during such a time is a mechanical fuel pump, which you will find at the bottom of the tank. When sugar enters this tank, it will solidify and create a muddy substance. This will prevent the engine from running efficiently and effectively. 

In recent years, however, the design of the fuel tank has changed. Not to mention, fuel filters are more advanced. Such will limit the negative impacts of sugar in a gas tank. Although your car can still demonstrate several problems, most of them are less serious. 

An Experiment to Examine the Effect of Sugar

gasoline water and sugar on the table

Over the years, several experiments have been done to investigate what sugar does in a gas tank. One of the most notable was a study by John Thornton, a forensics professor at the University of California. 

During the experiment, Thornton added radioactive carbon atoms to sugar. He mixed it with gas and took the sugar out with a centrifuge. It showed that only less than a teaspoon of sugar was absorbed by 15 gallons of gas. 

The experiment shows that when there is little sugar in the tank, it does not cause any serious problems. Nonetheless, adding a lot can have adverse effects, although it is not necessarily going to destroy the engine. 

In another experiment, a group called Project Farm examined the effects of sugar in a gas tank. Nonetheless, it wasn’t performed in a car. Instead, it was done in a lawnmower. Even so, you can expect the same effect in vehicles. 

The group added sugar in a four-stroke engine of a lawnmower. There was no explosion or any form of destruction. However, some sugar particles found their way to the valves and pistons. It did not prevent the engine from starting. 

The Filter Doing Its Job

fuel filter of a vehicle

One of the main reasons why sugar won’t kill the engine is the filter. Sugar particles can be as small as 200 microns. Most filters are effective in suspending these particles, preventing them from mixing with gas. This means that it won’t get too far in the engine system, so it won’t cause any serious consequences. 

Even if some of the sugar particles escape the filter that surrounds the fuel pump, there are others that can help. The fuel injectors and tank pump inlets also have their respective filters, which will catch the particles. 

Sugar Can Clog the Filter 

While it is true that sugar will not kill your engine, it does not mean that it has zero effect. The most serious consequence is that it will clog the fuel filters. This can be easily resolved by regularly changing the fuel filter to make it more efficient and effective. 

Signs That You Have Sugar in Your Gas Tank 

Worried if you have sugar in your gas tank? Below are some of the signs to watch out for: 

  • Power Surges 

As the sugar granules clog the fuel intake line, expect that there will be power surges. It is most apparent when you are accelerating or driving at high speed. It prohibits the engine from consuming the amount of fuel that it needs to sustain power. Sufficient fuel might enter during combustion, but the clog will eventually reduce gasoline flow, resulting in a surge. 

  • Engine Stalling 

Aside from power surges, your engine might also end up stalling once there is sugar in the gas tank. Any clog in the fuel transmission line prevents the gas from reaching the crucial components for combustion. The engine might stall either when you are accelerating or idling. There is a lurch when the car moves forward or backward, which will be immediately followed by stalling after restarting. 

  • Failure to Start 

As earlier mentioned, the most serious effect of sugar in a gas tank is that it clogs the filters. When this happens, there won’t be enough fuel that will combust for the engine to run, and hence, it will not start.

  • Requiring Less Fuel 

If you suddenly notice that your tank fills up quickly, it is another indication of the presence of sugar. It might have formed crystal at the bottom of the tank, and thus, it reduces the space available in the tank for fuel. 

  • Poor Fuel Economy 

Since sugar impairs the flow of fuel in the engine, it can result in poor fuel economy. Your engine requires the right amount of gas to work effectively. Not having enough gas will strain the engine and might make it consume more fuel than necessary. 

What to Do When There Is Sugar in Your Gas Tank 

As you would know by now, it isn’t the end of the world when there is sugar in your gas tank! It is not as serious as you might have thought. Still, it does not mean that you should not do anything. Below are some of the quick fixes that are worth a shot. 

  • Change the Fuel Filter 

The first thing to do, and often the most effective solution, is to change your fuel filter. Its main job is to collect dirt and debris, including solid substances like sugar crystals. Once the filter is clogged, it hurts the flow of gas, resulting in the inefficiency of the engine.

Replacing the filter does not only eliminate the sugar particles in the tank, but it can also help restore the maximum performance of the engine. 

  • Replace the Fuel Pump 

If the problem is left unattended for a long time or if there is a lot of sugar in the tank, the crystals can get through the filter and reach the fuel pump. It is a more complicated task and more expensive compared to changing the filters. 

  • Clean the Fuel Injectors

Another crucial component that you will need to clean is a fuel injector. You will need fuel treatment for the job. The latter is a liquid cleaner that will help remove the impurities in the fuel system, including sugar crystals. 

  • Take Your Car to a Pro 

If you are clueless about what to do or not confident in your DIY skills, the best solution is to take your car to a mechanic. It might be an expense, but it will be worth it given the professional attention and solution that the mechanic can provide. 

Water Is the Enemy 

Sugar will not mess with your engine to the point that it will stop working. If there is one thing that can ruin your engine, it would be water. Nonetheless, a few drops won’t be enough to end up in a catastrophe. It needs a lot of water before the engine sustains damage. 

Having water in the engine affects the combustion process. Water will sink to the bottom of the gas tank. The water will get into the engine cylinders, resulting in the failure to combust. You will need a fuel treatment to fix the problem. 

Also, find out how to properly dispose of old gas


Sugar cannot kill or ruin an engine. Nonetheless, it can get through the filters and cause several problems. The most serious is that it can clog the filter. This will prevent efficient fuel delivery, which can also add strain to the engine as it runs.