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2005 chevy trailblazer_ls
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Discussion Starter · #1 ·
The other day my wife and I were out and with the radio off, my window down and the motor running and I heard an intermittent hissing sound coming from the rear drivers tire area. It's not the tire, but I couldn't get a clear idea of where it could be coming from. I'm thinking maybe fuel filter? It makes a kind of half second purge sound. I sat there listening to it from the drivers seat for a second, the the motor kinda stumbled and revved to about 1200rpms. It's just strange. I got out and tried taking the fuel cap off thinking it was excessive tank pressure, but there was no burst of pressure when I removed the cap.
Any ideas? Anyone else had an issue similar?
I'm gonna crawl up under there tonight when my wife gets home with it, but having a little insight beforehand would be nice.
Thanks again!
 

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2004 gmc
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There are solenoid valves for fuel tank and charcoal canister pressurization (to test for leaks and how tight the cap is on) and venting/purge (to release the pressure after a diagnostic test). These diagnostics run secretly all the time, and if they fail, will light up the Check Engine light and throw a code. You must have caught them in the act. Nothing to worry about.

Item 11 is the vent solenoid

 

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2005 chevy trailblazer_ls
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124 Posts
Discussion Starter · #5 ·
There are solenoid valves for fuel tank and charcoal canister pressurization (to test for leaks and how tight the cap is on) and venting/purge (to release the pressure after a diagnostic test). These diagnostics run secretly all the time, and if they fail, will light up the Check Engine light and throw a code. You must have caught them in the act. Nothing to worry about.

Item 11 is the vent solenoid

Awesome. It hasn't happened again since, and it's kinda hard to track down something that's not doing anything while your looking :eek:
I'll keep my ear open for it. I started to think that maybe the "surge" was caused by the A/C. You know when you hear the clutch engage, the idle switches over.....
Here's to another 20,000 problem free (where's the toast emoticon?) This will have to do :coffee:excited:
 

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2004 gmc
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Oh, and if you missed my telling almost all noobs to do this, if you have erratic idle, especially if it's affected by the AC compressor cycling on and off, clean the throttle body. It's like the trailvoy miracle cure. Without a traditional PCV valve, the back of the throttle body beyond the butterfly valve can get as dirty as the bottom of your hog slop barrel after using it for ten years and then letting it dry out in the desert sun for another twenty.

http://forums.trailvoy.com/articles.php?do=viewarticle&artid=91
 

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2005 chevy trailblazer_ls
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124 Posts
Discussion Starter · #8 ·
Oh, and if you missed my telling almost all noobs to do this, if you have erratic idle, especially if it's affected by the AC compressor cycling on and off, clean the throttle body. It's like the trailvoy miracle cure. Without a traditional PCV valve, the back of the throttle body beyond the butterfly valve can get as dirty as the bottom of your hog slop barrel after using it for ten years and then letting it dry out in the desert sun for another twenty.

http://forums.trailvoy.com/articles.php?do=viewarticle&artid=91
You've got a 30 year old hog slop barrel? Gross!

Nah, I clean my TB about every 6 months or so, just for good maintenance. It's done the same interval as oil changes, K&N recharging and cleaning, and deep detailing the engine bay.
 
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