* Damage to the fuel pump: Fuel pumps are lubricated by the gasoline. Running the pump dry, especially with a potentially harsh chemical like fuel injector cleaner, can cause it to overheat and fail. This is a very expensive repair.
* Damage to the fuel injectors: While designed to handle cleaner, concentrated cleaner might not be ideal for the injector seals and components. It could potentially cause damage over time or even immediately.
* Clogging: Some fuel injector cleaners contain detergents that could separate or precipitate out without the gasoline to keep them suspended. This could clog the fuel filter or even the injectors themselves.
* Corrosion: Some cleaners can be corrosive, and the lack of fuel to dilute them might increase the risk of damage to the fuel system components, especially if the cleaner has a high concentration of alcohol.
* No Cleaning Effect: The cleaner needs the fuel to work effectively. It won't properly circulate and clean the system if there's no fuel to carry it.
In short, it's far better to add fuel injector cleaner to a nearly full tank of gas, as directed by the product's instructions. This ensures adequate lubrication for the pump and proper distribution of the cleaner throughout the fuel system. Never add it to an empty tank.
