EVAP leak

Tiny
DAD2CAMRIN
  • MEMBER
  • 2008 GMC SIERRA
  • 5.3L
  • V8
  • 4WD
  • AUTOMATIC
  • 130,000 MILES
I'm performing my own EVAP test. I plugged the smoke into the brake booster hose and blew in it and smoke came out my air-box on the other side. Why?
Wednesday, October 23rd, 2019 AT 5:13 PM

6 Replies

Tiny
DAD2CAMRIN
  • MEMBER
  • 6 POSTS
Engine light come on so I use my code reader and that said I had a small EVAP leak. So I replaced the vent valve solenoid and a new gas cap and it still didn't fix the problem.
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Wednesday, October 23rd, 2019 AT 5:20 PM
Tiny
JACOBANDNICKOLAS
  • MECHANIC
  • 109,758 POSTS
Welcome to 2CarPros.

A small leak can be at any point in the EVAP system and often times are nearly impossible to find.

What I suggest is this: Anytime I have such an issue, I don't even bother trying to find it without using a smoke machine. Basically, smoke is injected into the EVAP system at a very low pressure. When it reaches the leak, you will see where it is coming from.

Let me know what you find or if you have other questions.

Take care,
Joe
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Wednesday, October 23rd, 2019 AT 8:39 PM
Tiny
DAD2CAMRIN
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  • 6 POSTS
Instead of trying to enter the smoke at the brake booster should I try to enter the smoke at the port that's just above the intake manifold on the drivers side? Usually with like a green cap or something like that?
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Wednesday, October 23rd, 2019 AT 9:32 PM
Tiny
DAD2CAMRIN
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  • 6 POSTS
Should I just try to replace most of the EVAP line system with like a black gas line hose in place of the steel line because some of the line I have now is rather rusty?
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Wednesday, October 23rd, 2019 AT 9:35 PM
Tiny
DAD2CAMRIN
  • MEMBER
  • 6 POSTS
Po442 was the code that came up, small EVAP leak. What other place other than the brake booster hose should I hook the smoke machine up to?
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Thursday, October 24th, 2019 AT 2:44 AM
Tiny
DAD2CAMRIN
  • MEMBER
  • 6 POSTS
Where is the port that I hook up the smoke machine too for a small EVAP leak?
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Thursday, October 24th, 2019 AT 11:17 AM

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