5 Symptoms of a Bad Steam Canister Vent Valve
Your Evaporative Emissions Control (EVAP) system features a vapor canister vent valve that controls the amount of fuel vapors that are vented from the charcoal canister.
The breather valve and charcoal canister work together to direct emissions back into the engine, removing them during the combustion process.
But what happens when the vent valve doesn’t do its job? Let’s take a look at the most common symptoms of a bad EVAP bleeder valve and how much it might cost to replace if it does fail.
What is a Vapor Tank Vent Valve? Canister Vent Valve Solenoid Symptoms
The vapor canister vent valve is a component of the evaporative emission control system, whose primary function is to vent stored vapors from the charcoal canister to the engine.
There is a vacuum line that connects the intake manifold to the charcoal canister that contains the fuel vapors. The vent valve is located within the vacuum line to allow these vapors to enter the intake manifold at the appropriate time. Older vehicles use a vacuum type bleeder valve, while newer vehicles use an electronic bleeder valve.
How does a vapor tank vent valve work? When the bleeder valve opens, it can allow fuel vapors into the intake manifold. Once enough vapor has passed, the vent valve closes to stop any more fuel vapors from passing.
Symptoms of a Failed Vapor Tank Vent Valve
If your vapor canister vent valve is broken, the symptoms you experience may be worse than if your charcoal canister is broken. You need to understand these symptoms to differentiate between the two possible problems.
1) Check Engine Light
There are many reasons why the check engine light on your dashboard may come on. If your breather valve is damaged or worn out, it could cause the check engine light to come on. There is a sensor that detects when the vent valve is working. However, if there is no longer a signal coming from the vent valve, this indicates to the sensor that the valve must be damaged.
The sensor relays this information to the engine control unit, where you receive a “check engine” alert.
2) Rough Idling
When your car’s engine is idling rough, it won’t run smoothly. It will go at an abnormal speed while driving, especially when stopped at stop signs or red lights. The longer this problem persists, the smoother the engine will run. The worst thing that can happen is that the engine will stall completely.
Don’t let it get out of control. If the bleeder valve is the cause of the rough idle, there is usually a vacuum leak that affects the idle speed.
3) Car starting problems
If a defective vapor canister vent valve causes a vacuum leak, your vehicle may have difficulty starting. As a result, outside air enters the engine in an uncontrolled manner, disrupting the entire combustion process.
When uncontrolled air mixes with fuel inside the cylinder chamber, it will definitely cause engine problems. The most obvious problem is that the engine will not start.
4) Poor engine performance
If you are able to start your vehicle despite having a defective vapor tank vent valve, don’t expect a smooth ride. You will almost certainly notice a decrease in engine performance. In other words, your engine can’t produce as much power as it needs to achieve the required acceleration when you press the gas pedal. This is most noticeable when driving uphill or trying to pass another vehicle.
5) If it doesn’t pass the emissions test
As you know, the vent valve in the vapor canister is responsible for directing fuel vapors back into the engine, which prevents toxic hydrocarbons from escaping the exhaust pipe.
So if your breather valve isn’t working, it can’t redirect the fuel vapors to prevent them from escaping the vehicle. You know the big deal when you get an emissions test and fail it. That way you should be able to pass the emissions test.
