Rosco Coltrain

Ok I have the same exact issue you are having. Replaced the Solenoid at by the tank, the Charcoal canister, and the Evap valve on the motor. I did notice that when I replaced the Evap valve, some pieces of charcoal came out of it. On my next oil change I am going to have my mechanic go back through the vent lines to see if there are any more pieces in the lines as well as drop the tank to see if that shield was removed.

I learned next time to replace the charcoal canister first because by doing the solenoid first, I am worried I have charcoal in a brand new one and will need to replace it again.

keith jackson

I had the same issue with my 07 Tahoe and replaced the standard parts as well with no luck, finally had to go ahead and drop the tank and blow air through the lines and a bunch of charcoal pellets came flying out of the lines once it stopped and only air was coming out I put it all back together and problem solved.

Rick Lauder

Can you tell me what it costs to drop the tank and blow out?

Ladylilu

I took mine in for these issues. Replaced the canister (2nd one), Evap solonoid, etc. Dropped tank and blew the lines free, lots of charcoal. I think it was about an hour of labor but took them 2 hrs to clear the lines. So for the line blowout only (no parts) you're looking at labor only. Depends on how clogged the lines are. I've had this done 3 times now.

That being said, my 05 is back in the shop now, as I could never get more than a few gallons in after the initial 2 repairs. 2nd canister saturated and replaced. Still no luck. Theyre saying I need a new tank because there are sensors inside the tank that contribute to the issue if they are bad. Sort of last resort. So I'm on the hunt for a tank replacement. Curious if anyone else solved the issue like this.
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I've read a lot of posts and it seems that it's really an issue of troubleshooting. Could be the first obvious repairs but you can't fully know until those... Fail. Trying to keep my truck alive after all the typical issues for these - cylinder head leak, blower motor fail, all the fun hvac and electrical issues, sunroof leaks. She runs like a dream... If only she took fuel lol.

172k on my 2005 4wd 5.3 v8 with auto ride (auto ride died several years back)
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Ladylilu

Ok, I'm desperate... I've replaced the canister (twice), the vent solenoid, blown the lines out (3 times) and finally just replaced the fuel tank and lines (fuel tank replaced and new canister at same time). Takes fuel now, but I got the small Evap leak code again today. 2 half-tank fill ups since repair

I don't even know what to do next. If anyone has nuggets of wisdom, I'd sure appreciate it.

tech2

post the code number
include your vehicle make, model, year and engine

Ladylilu

2005 Tahoe 5.3L , 173k mi.

The last two posts in the thread are both from me, so there's a little more info on my situation.

New code is P0442 -
Evap system small leak detected
thank you!

tech2

so some new parts but the leak code.
question...how does the evap system determine a leak is present?
In your system, after the vehicle is shut off....the normally open vent solenoid is closed and the normally closed purge solenoid is left closed. this seals the system. the pcm monitors the fuel tank pressure sensor and expects a change is pressure ( due to heat soak). a leaking system would show little pressure change.
so if the expected psi change does not occur...the pcm thinks a leak is present.

-so the fault possibilities are: a leak is present or the ftp sensor reading is not changing.
-a shop could monitor the pressure sensor reading for change when the purge is open. if the reading changes, the sensor is ok, you probably have a leak. if it doesn't change the vac/psi reading...you may have a sensor or wiring problem to the sensor.

if the senor is good-smoke test the system...the evap smoke machine has a flow meter.....the shop closes the vent solenoid and fills the system thru the evap service port. They monitor the flow meter...if the flow meter zeros...no leak is present. if the flow meter does not zero...a leak is present. I would open the system at a easy access connection near the half way point and smoke both sides....one sid e will leak the other will seal....this eliminates 1/2 the system...the leak is on the other side. continue moving down the line untill you isolate the leak point.

Jerry the bulldog

it's the Fuel tank pressure regulators that doesn't allow gas to go in the tank since it's pressurized...you welcome these other guys are idiots

tech2

fuel tank pressure regulator isn't even a part. the fuel pump has a pressure regulator but it won't effect fuel fill up in any way. Do better b4 calling other members names.