It is a common belief that putting sugar in a gas tank will cause a syrupy mixture that will immediately seize the engine. What truly happens, however, is that the sugar does not dissolve. The particles of sugar are caught by the filters that are in the fuel line. Therefore, the sugar itself will not make it to the engine. However, if enough sugar is put in the tank it can eventually clog the filters. This can lead to a clogged fuel line which may, in turn, cause issues with the engine.