buddy i bet you have dirt or sand stuck in your vent valve and canister. they are part of your evap system. pretty common in rural areas around here. it isnt located in your tank though. it looks like its just to the left or right of the tank and should have three hoses comming off of it. one of the hoses goes strait to the vent valve, and the vent valve will have one more hose comming off of it. it will be a round cylinder with a hose at the bottom of one side and the top of the other. your canister will be rectangle and flatt. about four or five inches by about 10 to 12 inches. hope you get this one figured out. DO NOT LET YOUR MECHANIC CHANGE YOUR GAS TANK. YOUR PROBLEM WILL STILL BE THERE.

 

if you diss connect some of the hoses on your canister and your valve look for sand or dirt inside of them. if there is a pretty good amount than thats your problem. keep us updated.

 

Thanks a lot!
I'll update the post after the service.

Best Regards

Oliver

 

My '07 threw a P0446 and P0455. They had to replace the 1-valve (25962085), 1-solenoid (19208702), 4-hose htr (12368236), and 2-clamp (744245). As best I can remember it didn't require dropping the tank.

There was a bulletin #2292102

 

So I went to the service shop but could not locate the vent valve
I found the solenoid canister but the vent valve seems to be well hidden.

I took a picture, maybe you could please show me where to look for it.

Regards

 

im not 100 % sure on your tahoe but on my 2000 suburban it is just to the rear of the gas tank. I just happen to have the exact valve at my shop ill take a pic of it and post it here tommorow evening. A friend bought a 2008 tahoe that was wrecked and parted it out. So i grabed a few things that i thought i might need. but i can tell ya IT IS NOT in the tank

 

On mine it was all part of one assembly.

Did you give them the P/Ns and bulletin no.?

 

I don't know what a P/Ns or bulletin is. I apologize but my English knowledge are not that good and abbreviations are a total mystery to me.
Anyway, I didn't show them anything but our topic here and a few pictures that I found out that weren't appropriate.

Standing by for the pics.

Thanks and Regards

 

There ya go hope it helps

 

The P/Ns (part numbers) and technical bulletin number are in post #14.