Why Are Purge Valves Widely Used

Back in the days, fuel vapor from car fuels was considered waste and a vent was put in place to dispose it right into the atmosphere. However, developments in technology have shown that fuel vapor can be something more than just waste. Yet, effectively using the fuel vapor in olden day cars was quite impossible, as they do not have a system designed for the task. Over the years, the car manufacturing industry have seen a lot of improvements and today, each car has its own Evaporation Emission control (EVAP) system. A system designed to effectively use the fuel vapor from the car’s fuel and maintain the right air-fuel ratio of the car. Unlike the vents in old cars, the EVAP system is designed to restrict the EVAP pollution which is emitted in form of vapor, caused by the burning of fuel in cars from reaching the atmosphere. The system traps the vapor in a charcoal canister where it is then released into the engine at regulated amounts, to be burnt as regular fuel.Image result for Purge Valves

The EVAP system consists of a very important component – the Purge Valve. The Purge Valve which is also known as the Canister Purge Valve is responsible for controlling the flow of fuel vapor in the engine. It is an electrically-operated solenoids that is digitally controlled by the engine computer. When the car engine starts to run, the purge valve is gradually opened by the engine computer – based on the warmth of the car – to slowly allow some fuel vapor to be moved from the charcoal canister into the engine to burn like regular fuel.

The engine computer has several sensors that it uses to monitor the flow of fuel vapor in the engine. When the amount of fuel vapor flow in the engine is higher or lower than expected, the engine computer issues a warning by illuminating the “check engine” light. The purge valve is a very crucial component of a car and a faulty or damaged purge valve can significantly lead to several engine and performance problems.

Why Use A Purge Valve

Purge valves are widely used basically for regulating the flow and use of fuel vapor in the car. However, the Purge Valve can also be useful in other ways such as maintaining the right air-fuel ratio in the car. The air-fuel ratio is the ratio of fuel vapor and actual fuel that is combined to smoothly run the engine. This ratio is maintained by the purge valve. When the air-fuel ratio is disturbed, mostly through a faulty purge valve, a vacuum leak is created. A vacuum leak in the engine can give rise to several engine and performance related problems.

Another reason why Purge Valves are widely used is to maintain a high gas mileage. Gas mileage is the ratio of the number of miles travelled to the number of gallons of fuel used. Simply put, it is the fuel efficiency of a car. With the Purge valves, fuel vapor can be burnt as normal fuel in the engine. This increases the efficiency of a car’s fuel. If the purge valve get faulty, it may stay closed, thereby reducing the amount of vapor that enters the engine. This can significantly reduce the gas mileage of a car.


In modern cars, Purge Valves are widely used for the same important reason – to regulate the flow and use of fuel vapor in the engine. This makes the Purge Valve a very important component in the engine. Whenever a purge valve gets faulty or damaged, it could give rise to several engine problems and may even cause the engine not to start. An effective maintenance routine should be put in place to make sure the purge valve is in good condition. Purge valves are inexpensive and they should be replaced once they get damaged or faulty, to prevent further problems.