How to test a purge valve without a vacuum pump? (4 methods)
Content
Here are four different methods for those looking for ways to test a purge valve without a vacuum pump.
While it's easy to test the purge valve with a vacuum pump, you may not have a vacuum pump every time. On the other hand, finding and buying a vacuum pump is not easy. With all of this in mind, looking into a few alternative ways to check for a faulty purge valve might not be the worst idea in the world. So, in this article, I hope to teach you four simple methods that you can use to test your purge valve effortlessly.
Generally, to test a purge valve without a vacuum pump, use one of these four methods.
- Check purge valve click.
- Purge valve stuck open.
- Check the integrity of the purge valve.
- Check the resistance of the purge valve.
Read the respective step-by-step guides for each method in the article below.
4 Easy Methods for Checking a Purge Valve Without a Vacuum Pump
Method 1 - Purge Valve Click Test
In this method, you will test the purge valve click sound. When the purge valve is energized, it opens and makes a clicking sound. If you can identify this process correctly, you will be able to determine the condition of the purge valve.
Quick-Tip: The purge valve is part of the vehicle's EVAP system and aids in the combustion process of fuel vapors.
Things You'll Need
- Rechargeable battery 12V
- Multiple alligator clips
Step 1: Locate and remove the purge valve
First of all, find the purge valve. It should be in the engine compartment. Or it should be next to the fuel tank. Disconnect the mounting bracket and other connectors. As for the other connectors, there are two hoses and one wiring harness.
One hose is connected to the carbon adsorber. And the other is connected to the inlet. The harness supplies power to the purge valve and connects to the two valve power terminals.
Step 2 Connect the purge valve to the battery.
Then connect two alligator clips to the positive and negative battery terminals. Connect the other ends of the alligator clips to the purge valve terminals.
Step 3 - Listen
A properly functioning purge valve will make a clicking sound. So, listen carefully when connecting the alligator clips to the valve. If you don't hear any sounds, you are dealing with a faulty purge valve.
Method 2 - Purge Valve Stuck Open Test
This second method is a little old fashioned, but it's a great way to test the purge valve. The best thing about this is that you don't have to remove the purge valve from the car and no tools are required.
Note: You already know the location of the purge valve; so I won't explain it here.
Step 1 - Disconnect the canister hose
First, disconnect the hose coming from the coal tank. Remember that you must not disconnect the hose that comes from the inlet. Keep it intact during this testing process.
Step 2 - Start the car
Then start the car and let it idle. This is an important step to apply vacuum to the purge valve.
Quick-Tip: Remember to apply the parking brake during this verification process.
Step 3 - Disconnect the wiring harness
Then locate the wiring harness and disconnect it from the purge valve. When you disconnect the wiring harness, you don't have to worry about any wiring problems (you don't check the wire connections in this testing process).
Step 4 Place your thumb on the canister hose port
Now wet your thumb and place it on the hose port of the canister. If the valve is working properly, you won't feel anything.
However, if you feel any vacuum, the purge valve is defective and needs to be repaired.
Method 3 - Continuity Test
Continuity is one of the best ways to test a purge valve. If something inside the valve is broken, it will not show integrity.
Things You'll Need
- Digital multimeter
Step 1: Disconnect the purge valve from the vehicle.
First locate the purge valve and disconnect it from the vehicle. Don't forget to disconnect the two hoses and wiring harness.
Quick-Tip: During this process, the vehicle must be turned off.
Step 2 - Set the multimeter to continuity
As I mentioned earlier, you are going to test for continuity. Therefore, set the multimeter dial to the continuity symbol. This is a triangle that has a vertical line. Also connect the red connector to the Ω port and the black connector to the COM port.
After you set the multimeter to continuity, the multimeter will beep when two probes are connected. This is a great way to test your multimeter.
Step 3 - Connect the multimeter leads
Then connect the multimeter leads to the two purge valve power terminals.
Step 4 – Evaluate the Results
The purge valve is working properly if you hear a beep. If it is not, the purge valve is faulty.
Method 4 - Resistance Test
The resistance test is the same as in the third method. The only difference is that here you are measuring resistance.
The resistance of the purge valve should be between 14 ohms and 30 ohms. You can check the purge valve according to these numbers.
Things You'll Need
- Digital multimeter
Step 1: Disconnect the purge valve from the vehicle.
First locate the purge valve and remove the mounting bracket. Then disconnect the two hoses and wiring harness.
Pull out the purge valve.
Step 2 - Set your multimeter to resistance settings
Then turn the dial of the multimeter to the Ω symbol on the multimeter. If necessary, set the resistance range to 200 ohms. Remember to connect the red connector to the Ω port and the black connector to the COM port.
Step 3 - Connect the multimeter leads
Now connect the multimeter leads to the purge valve power terminals.
And pay attention to the resistance valve.
Step 4 – Evaluate the Results
If the resistance value is between 14 ohms and 30 ohms, the purge valve is working properly. The purge valve is broken if you get a completely different value.
How do I know if the purge valve is defective?
There are quite a few signs by which you can determine the malfunction of the purge valve. These symptoms may occur regularly or occasionally; you should never ignore them.
- Check if the engine light is on.
- Problems with starting the car.
- Failed emission test.
- Damaged spark plugs or gasket.
- Engine misfiring.
If you find any of the above symptoms, it might be time to get tested. However, not in all cases, the cause of the above symptoms may be a malfunctioning purge valve. So, testing is the best way to dispel any doubts.
Use simple testing methods such as the click test or the hang open test. Or take a digital multimeter and test the purge valve for continuity or resistance. Either way, these methods are excellent when you can't find a vacuum pump. Even if you have a vacuum pump, the methods above are easier to follow than using a vacuum pump.
important: If necessary, feel free to seek the help of a professional for the above testing process.
Take a look at some of our articles below.
- How to check the purge valve with a multimeter
- Where is the engine ground wire
- How to test a coil with a multimeter
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