Does a Faulty Canister Purge Valve Increase Fuel Consumption?

[ORowan]

A faulty canister purge valve can significantly increase fuel consumption. Here are the reasons for the increased fuel usage: 1. Fuel tank sealing: Due to the fuel tank's airtight design, fuel consumption creates negative pressure inside the tank. Under this negative pressure, gasoline evaporates more easily into fuel vapor compared to normal atmospheric pressure. When the engine is off, the charcoal canister stores this fuel vapor mixed with air in the micropores of its activated charcoal, preventing the vapor from escaping into the atmosphere. During engine startup, the solenoid valve between the charcoal canister and intake manifold opens, delivering the stored fuel vapor to the engine for combustion. 2. The canister purge valve helps reduce fuel consumption: If the valve fails, the vehicle may experience air leaks, allowing fuel vapor to enter the cylinders before ignition. This results in an overly rich air-fuel mixture, making the vehicle harder to start and consuming more fuel. Additionally, the excessively rich mixture leads to incomplete combustion, prompting the engine ECU to compensate by leaning out the fuel injection, which also contributes to higher fuel consumption.