The fuel consumption of a 350 MerCruiser engine can vary depending on several factors, including boat weight, hull design, cruising speed, and other operating conditions. It's essential to note that fuel consumption is typically measured in gallons per hour (GPH) or liters per hour (LPH) rather than a fixed amount.
That being said, a general estimate for a 350 MerCruiser engine is around 10 to 20 gallons per hour (GPH) or approximately 38 to 76 liters per hour (LPH) at cruising speed. However, please keep in mind that this is just an approximation, and the actual fuel consumption may differ based on the specific circumstances and variables mentioned earlier. It's always best to consult the manufacturer's documentation or consult with a qualified boat dealer for more precise fuel consumption figures for your particular setup.