Does a coolant hose go through the fuel injection system of 2000 Chevy Blazer 4.3 liter engine?
No, a coolant hose does not go through the fuel injection system of a 2000 Chevy Blazer 4.3 liter engine (or any gasoline engine, for that matter). The cooling system and the fuel injection system are entirely separate. They might be located near each other in the engine bay, but they don't share any components.