How can I test the purge solenoid?

Tiny
IMAGING
  • MEMBER
  • 1999 BUICK REGAL
  • 3.3L
  • V6
  • 2WD
  • AUTOMATIC
  • 123,000 MILES
Saw a video where the engine was on and they disconnected the solenoid and disconnected one of the hoses, wet their finger and covered the valve to see if there was any vacuum and if there was then the solenoid needed replacing. Is this a proper way to test it without removing the solenoid completely?
Sunday, October 3rd, 2021 AT 1:27 AM

3 Replies

Tiny
KASEKENNY
  • MECHANIC
  • 18,907 POSTS
Short answer is no.

Here is the long answer: This is only testing to find out if the purge is open to the intake manifold to allow the vacuum from the engine to pull in the vapor.

What if the purge is stuck open which is the normal failure? This will allow vacuum all the time which means it is pulling fuel vapor when it should not, and this will cause hesitation or stalling because it throws off the air fuel mixture.

So doing this test, that just proves that it is not stuck closed but that again proves another issue. What if they test it when the valve is closed? Then they are going to suspect that the solenoid is stuck closed and replace it.

So, I say all this to say, this test is one of those tests that gets many vehicle owners frustrated because they assume it is good info, but it really doesn't tell them anything because the only way it is good info is if they know what the purge is supposed to be doing at the time, they are testing it.

So, the only way this is a definitive test is if they know what position the purge is supposed to be in, open or closed, and test it this way in both position and see that it is open and closed.

The proper way to test this is attached below. I would start with checking for codes as this is monitored and if there are no codes then it may be fine but should still be monitored as shown below.

https://www.2carpros.com/articles/checking-a-service-engine-soon-or-check-engine-light-on-or-flashing

Let me know what questions you have. Thanks
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Sunday, October 3rd, 2021 AT 7:36 AM
Tiny
IMAGING
  • MEMBER
  • 151 POSTS
The code is P0442 that is showing. Now, I found the evap purge solenoid by the engine on the left. Is there another vent valve by the driver side rear tire by the gas tank that I should check?
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Sunday, October 3rd, 2021 AT 10:09 AM
Tiny
KASEKENNY
  • MECHANIC
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Yes. The vent valve is on the canister that is back by the tank. However, that code is for a small leak so I would run through this testing for this code as it could be a number of different things.

Basically, this system can have external leaks like the gas cap but also internal leaks through the purge into the manifold or the vent valve on the canister. This system needs to be able to seal itself so if it can't it sets this code.

These can be very annoying to fix so let me know if you have questions.

See the info for the test and valve below. Thanks
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Sunday, October 3rd, 2021 AT 6:15 PM

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