What Happens When You Put Sugar in a Gas Tank?

by Doug DesjardinsUpdated August 01, 2023

Putting Sugar Into a Gas Tank

Just about everyone has heard of the notion that putting sugar in a gas tank will destroy a car engine. But is it really true? While putting sugar in a car's gas tank won't always destroy an engine, it can cause some major damage and, in most instances, cause the victimized car to stall and require major repairs.

What Happens to the Sugar

Sugar is a scourge to car engines because it doesn't dissolve in gasoline. This means sugar poured into a gas tank will get sucked into the fuel lines and begin clogging up a vital part or parts of your engine's fuel system. It can disable the fuel filter, the fuel pump and the fuel injectors, depending on how much sugar is loaded into a gas tank and where it accumulates. Wherever it ends up, the sticky ball of sugar will block the fuel flow and cause your engine to stall and not start again. And once a mechanic takes the engine apart, repairs can be expensive, especially if the sugar reaches your carburetor or fuel injectors. You'll also need your fuel tank emptied and cleaned and your fuel lines flushed out or replaced. So while sugar won't exactly destroy an engine, it can destroy parts of your engine that are expensive. Not surprisingly, the sugar-in-the-gas-tank tactic was developed in the early 20th century as a guerrilla war tactic to disable enemy vehicles.

Some Exceptions to the Rule

There are cases where sugar can completely ruin an engine. If enough sugar gets by the filter, pumps and fuel injectors, it can get into the engine itself, and build up in the valves and piston rings. Once there, it will eventually harden into a mess that will require a complete engine overhaul or a new engine. But the chances of that happening to new car models is slim because most cars today have sophisticated fuel filter systems designed to catch contaminants and prevent them from reaching the engine. The bottom line is that putting sugar in a gas tank really can cause some damage. The only variable is how much damage it causes.

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