How long should you run an exhaust blower before starting the engine?

Running an exhaust blower for a sufficient period before starting the engine is critical for ensuring safety on a boat. The correct duration is about 4 minutes. This time allows any potentially harmful gasoline vapors, which may have accumulated in the bilge area, to be cleared out. Gasoline vapors can be highly flammable and pose serious safety risks, including the possibility of an explosion.

By running the exhaust blower for this recommended duration, you significantly reduce the risk of igniting these vapors when the engine is started. It also ensures that the air in the engine compartment is adequately ventilated, which is essential for both safety and proper engine function.

In contrast, running the blower for a shorter amount of time, such as 1 or 2 minutes, may not effectively eliminate all hazardous vapors, leaving a potential risk when starting the engine. Running it for 10 minutes, while thorough, is typically unnecessary and not commonly recommended, making 4 minutes the standard practice. This approach balances safety with efficiency.