Trouble filling up the gas tank

[Goodfootin]

First off, Rooster, thank you for that very detailed write up.

I have a 2005 Tahoe Z71, same thing- hard to fill and get loud whistling noice. I changed the Evap Canister but no luck. Changed purge valve but again no luck (but I didn't notice pellets in there as some have). My next step is charcoal canister, but here is my question. Has anyone had the problem go away after changing the charcoal canister, or has everyone had to continue to clearing the lines?

 

[treehan77]

Id would be damn sure your new evap actually works. I got a new ac delco and it didn’t work. You can bench test it with 12 v.

 

[Goodfootin]

Id would be damn sure your new evap actually works. I got a new ac delco and it didn’t work. You can bench test it with 12 v.

Yeah, I read that. Great point. I will. Thank you!

 

[JollyRoger01]

Check the vac line attached to the solenoid behind your TB. My 05 charcoal canister went out and filled the line with little beads of coal.

 

[treehan77]

I had drop the tank and blow the lines out. Replaced the pump while I was in there, and my gas light stopped coming on randomly lol.

 

[Goodfootin]

Thank again in advance for any ideas. I should also admit that I am likely much more ignorant than the average person on this board, so please bear with me. I have a limited tool box and, but usually can find someone with what I need to borrow. I would also be crippled without youtube videos showing exactly what to do.

As stated previously, I replaced the evap canister and purge valve, but no luck. After reading about charcoal pellets in the purge valve, I checked the one I had previously removed, and sure enough, it had quite a few. I pulled the new valve I had installed, and it has 2 or 3 pellets in it. I have not blown out that line yet, but will as soon as I can get a pump to do it.

I pulled the charcoal canister, and sure enough, pellets went everywhere (including in my ear). I shook what I could out of the tank vent line, but from reading previous posts, I understand there are likely more pellets in the line that need to be cleared. I installed a new charcoal canister, but it did not solve the refueling problem. Here are my next steps.

1. I still need to bench check the evap canister/solenoid to make sure it was not defective. Access to a tester (and the skills to use it) is limited during social distancing, but I'm working on it.

2. JollyRoger01 said to check the vac line attached to the solenoid behind the TB. I've racked my brain, but can't figure out what TB stands for. I assume you are taking about the Evap canister/solenoid. There is only one line on that canister and it appeared to be clear when I pulled everything off to replace the new charcoal canister.

3. Rooster's write up said he finally solved the problem by clearing the tank vent line that attaches to the charcoal canister. Pulling a vacuum on the line didn't do the job, but blowing back in to pressurize the tank and then letting it out blew out the pellets. Rooster used the line between the solenoid and the charcoal canister. But his pics show that it has a different attachment than mine. Is there any reason why I should not be able to achieve this by using the line between the charcoal canister and the tank? Also, how much pressure should I apply (in layman's terms)? Can I do damage by over-pressurizing?

Thank you for any advise, and for your patience.

 

[treehan77]

TB is usually throttle body. Assume he means the one on top of the engine. Did you check that one? Mine had pellets up there also. I removed the line and blew air that way and back. More pellets. I eventually just dropped the tank and blew out the lines, I could never get all the pellets out with the tank in

 

[treehan77]

Do you have a 12 drill battery? Basically you just need to supply 12v to that canister plug, and see if it clicks open/closed. You can test by blowing in it. If you apply voltage, it will flip closed/open, stopping your ability to blow thru it. Can’t remember if it’s normally closed or open! Blow into it without voltage will tell you, voltage should do the opposite.

 

[Goodfootin]

Thanks Treehan. The only line towards the engine I pulled was the one to the purge valve. I don't know what the other one is. I'd happily check it if I had any idea how.

 

[treehan77]

You can remove the end on top of the engine. You have to take off the engine cover and it’s basically right in the middle towards the front. It has a gray or green press clip thing and a rubber gasket.