Sugar in a gas tank won't damage your engine, but water can cause big problems.
Everyone has heard the urban legend that if you put sugar in a gas tank, the engine will certainly break down. What is the reason? Will the sugar turn into sticky jelly and clog moving parts, or will it caramelize and settle as carbon deposits? Can someone's mean joke really bring so many problems?
In fact, the chemical properties of sugar have nothing to do with it. Any solid particles trapped in the injector or cylinder can be harmful; to protect against them, there is a fuel filter.
Sugar Dissolution Experiment
The fact is that sugar does not dissolve in gasoline and cannot get into the engine. This theoretical reasoning is convincingly supported by an experiment conducted in 1994 by forensic science professor John Thornton of the University of California, Berkeley. The professor mixed gasoline with radioactively labeled sugar and ran the mixture in a centrifuge, and then measured the radioactivity of the gasoline to calculate the amount of sugar dissolved. It turned out that only about a teaspoon of sugar dissolved in almost 60 liters of gasoline, and this amount is clearly not enough to cause problems. If your gas tank was incomplete at the moment when it was "sweetened", it will dissolve even less, thanks to less solvent.
Sugar is heavier than gasoline, so it will simply settle to the bottom of the gas tank, reducing its useful volume. If you have to drive on a rough road and some of the sugar is shaken up, the fuel filter will handle this small amount. More frequent filter changes may be required for some time, but sugar is unlikely to clog the fuel supply system. If the "well-wisher" poured out a whole bag of sugar to you, then it is better to drive the car to the service, where the tank will be removed and cleaned. This procedure is in any case cheaper than replacing the engine.
What can really kill an engine?
Water in the gas tank can cause the engine to stall because it interferes with combustion. Water is heavier than gasoline and gets into the fuel line. However, this is not a verdict, the problem is solved with the help of moisture neutralizers, in the assortment of auto shops presented on the shelves.