Purge valves might not be the first devices that spring into your mind when the topic of important car compartments is brought in.
But do you know that without these small devices, your car might encounter disastrous evaporative emission/air circulation issues?
Worse, rough idling accidents may happen amidst your trip without warning, causing numerous nuisances and expensive costs!
So what’s a purge valve? And what does a purge valve do exactly, and is there any tip to treat them when they fail to perform their designated jobs?
This article by Bryan’s expert team is here to address your concerns. Keep scrolling.
What Is A Purge Valve? What Does A Purge Valve Do?
What Does The Purge Valve Do?
Purge valves are integral to any vacuum material system (particularly in cars and motor vehicles).
They provide on-and-off material flow into conveying lines, purging it with air near the loading cycle’s endpoint – in this case, the car’s engine.
Hence, the purge valve purpose is to prevent quality and contamination problems in the engine’s emission tank, purging it clear before other substances are transferred via the same line.
In most cases, the valve will be connected to one distribution box, where materials/air/emissions can flow to the conveying system, cleansing the remaining material inside the line.
Material flow and infeed are frequented by the removable tubes installed deep inside the distribution boxes.
How Does It Work in Modern Vehicles?
One purge valve compartment controls the flow of regular fuel vapors.
When the conveying system starts to cycle to respond to vapor demand, the valve will not be energized, open to let resin flow through to the tank.
Once sufficient vapors have been produced, the valve will close to open the port instead, allowing the conveying line and valve to absorb floods of air.
These floods purge the car’s conveying line and valve to its destination receivers, removing excess vapor that might otherwise pollute/discolor the next vapor/fuel flowing through.
After this purging process finishes, your car engine has just completed a full vacuum transferring cycle, keeping vapor from exuding into the outside atmosphere.
Remember that the valve’s port can connect to either dry air or ambient air flow drawn through the fuel fill inlet.
The former (dry air) is highly recommended when the car tank moves dry emissions to storage hoppers for further processing.
Drivers can also retrofit purge valves for existing automobile systems that lack air-purging capabilities.
What Are The Signals of A Bad Canister Purge Valve
Your Engines Struggle to Get Started
Does the engine refuse to be ready no matter what you do? Then the purge valves might be the reason.
As the purge valves’ usual task is to maintain the fuel tank’s balanced pressure, their failure to do that will flood the fuel back to the filler pipes when your engine switches off.
Hence, it will encounter troubles when restarting.
Yoru Engine Runs Rough or Stalls
If the car’s engine stalls frequently or seems like it runs rough, it’s time to inspect the purge valves.
When the valve gets stuck in the open position, it will create vacuum leaks that impact the engine idle.
Rough engine performances also lead to black smoke billowing from within the tailpipe and poor mileage.
Bumpy Acceleration
You will realize this symptom instantly when the car takes forever to accelerate after you have stepped on its gas pedal.
That’s understandable; a smooth-running valve will remove excess vapors and fuel from the engines – as previously mentioned – to foster seamless speedup.
Their breakdowns, otherwise, will inevitably lead to bumpy trips.
Blinking Check Engine Lights
Although intermittent flashing check engine lights can stem from numerous reasons, we still suggest you check the snorkel purge valves first.
If they are stuck, your engines will misfire, causing the warning lights on your dashboards to switch on in response.
Your Engines Gives Off Strong Fuel Vapor Smell
Bad purge valves with improper closing will leak the fuel, resulting in a strong engine smell like gasoline.
So please do not ignore any strange odor coming from the engine; stop the car to check it immediately!
Gasket Damage and Wear
Another consequence of faulty purge valves is the pressure buildup within the car’s combustion chamber.
The gasket and rubber seals will destroy themselves over time, leaving behind severe damage and deteriorating gas mileage.
Why Does It Go Bad?
Faulty Connectors or Wiring
Damaged/faulty wirings in the valves are the biggest culprit of its defect. Similarly, connectors that have been corroded or dirty over time also damper the valve’s mechanism.
Malfunctioning Solenoid
The solenoid takes charge of closing/opening the valve – another reason why some call purge valves “purge solenoids.”
Even a child can imagine what will happen if these solenoids fail to properly handle the valve’s opening and closing.
Dirt Buildup
Needless to say, dirt causes severe valve blockage and hampers its operation.
Aside from dirt, corrosion (due to frequent usage), debris, and fuel deposits are possible reasons for the blockage that you should consider.
Leaking Purge Solenoid Valve
Leaking valves obviously mean one thing: the tank pressure is compromised. As the car turns off, fuel will return into the filter pipes of the very same valves that are currently leaking.
Broken ECU (Engine Control Units)
Technical issues and incorrect settings are common roots behind a non-working engine control unit.
And since the engine control is broken, the purge valve’s engine pressure naturally follows suit, refusing to cycle correctly.
How to Fix Broken/Defective Purge Valves
1. Go to Mechanics for Proper Diagnosis/Replacement
Your best bet to fix faulty canister purge valves is to go to a trusted repair shop and ask for a canister purge valve replacement.
In that case, expect to spend around $150 to $300 to have the job performed properly.
Of course, this estimation cost also fluctuates across numerous external factors, such as the vehicle’s model/year and how severely the valve has destroyed the engine.
One way to save the cost is to replace it yourself. Nevertheless, remember that you also have to spend some money on tools and equipment, which roughly costs the same as professional services.
Not to mention, some technical skills are also required, which very few drivers have.
2. Clean The Valve At Home
To keep debris buildups at bay, clean the purge valves properly. Here are simple steps to do so:
Step 1. Spray some MAF or carb cleaner into both purge valve solenoid tubes and the charcoal canister.
Step 2. Use your hands to cover its ends and give the valve a good shake. Then cover them and wait for a few minutes.
Step 3. Uncover the tube to let liquids drain out. You can repeat steps 1-3 several times until there’s no dirt and grime in the liquid.
Step 4. Spray some contact cleaners on the car switches and valve connectors. Leave everything to dry on its own, and you are good to go.
Conclusion
What is a purge valve on a car, and what does a purge valve do? How can novices/first-timers realize its symptoms of malfunctioning?
Bryan’s well-researched guidelines have addressed the mechanism and purpose of a purge valve in detail, providing several treatment solutions to guarantee the car’s smooth run once again!
Though some fixes can be a bit too complicated for average/inexperienced riders, we trust you can do some simple cleaning at home without difficulties.
Keep a consistent cleaning schedule at least once a week, and always inspect the valve after every ride to identify unusual signals as soon as possible.