domdes

My truck goes back to the dealer tomorrow. I asked them to drop the tank. Hopefully they will fix it this time.

Michael Sprague

Musky Hunter 67. Did you ever resolve your issue? I'm having same issue and replaced the vent solenoid first (didnt fix), followed by the vent canister. My canister was faulty and filled my vent lines with charcoal bits. I blew out the lines attached to the canister and put the new canister on which still didnt resolve my issue. Not sure what to try next.

sjdave

Having same issue on 2006 Sub. I am suspecting the small hose that runs from the top of the filler neck to the top of the tank. An ex chevy Tech told me this is how the gas pump gets it's pressure reading, through the air path from the tank up this hose to the filler neck. That makes sense, if the fill tube is full of gas pumping at a high rate, the tank pressure won't be felt back up the fill tube. I noticed there is a plastic fitting half way down that tube to the tank, is that a check valve?? Maybe it is stuck?

domdes

No, my issues are not solved.
I took it back to the dealer and they didn't have enough time to figure it out.

kenmanme

I'm not sure if you mean the disconnect close to the tank, it kinda looks like a plastic fitting, but there is no valve there, it's how that small line gets disconnected from the tank line. When i tore mine apart, there was a brass piece near the top of that small line, where it connects to the filler neck. I can't call it a check valve, it was more like a restricting device, just a small hole in a brass plug. I replaced that vent line with new material, and I did not put the brass piece back in. I still had fuel-up issues.
My problem was eventually determined to be the lines that run above the tank, but I replaced just about everything before I discovered that.
Anyway, now the truck has no issues at all, but that little brass piece is still sitting on the workbench. whatever it was designed to do doesn't seem to have much impact.

VickieS Vickie

Rosco Coltrain

I've got the same issue with my 07 Tahoe LT 2WD that started at about 225K miles. I replaced the solenoid first, didn't fix it. Charcoal canister, which we found was bad and could have been the root cause as charcoal fell out of it when removed and still didn't work. Checked all the lines and found no issues. I read someone the Evap valve on the motor is the last component to the entire system and tried that. I removed that, charcoal fell out of it. Put the new one on and it got better but still not fixed. Now back to .2 gallons per click and takes forever to fill the tank..

I am hoping it's just some leftover charcoal in the lines and will have all the lines checked again on my next oil change. I am considering having the tank dropped as well because I read somewhere if the shield on the top of the tank is missing, it can crush the lines and it will pass all tests making it appear like nothing is wrong.

Pilot808w

I had the same problem on an '04 Avalanche, slow fueling. I replaced the vent valve to no avail. I took the charcoal canister down for inspection and found liquid fuel inside. Blew it out with compressed air, still no joy. I ordered a new canister, but when it arrived I was afraid if that wasn't the problem I would get liquid fuel in the new one theoretically ruining the new one. So I cut the case on the old canister and gutted it. It was a clear pass through and still wouldn't fill properly. It ended up being liquid fuel trapped in the filler neck vent line. Apparently the vent valve went bad and caused liquid fuel to get into the canister, vent valve and the vent line for the filler neck. I took the connector apart and blew compressed air into the tank. I could hear the liquid clear and the air venting through the vent valve as you would expect. Reconnected everything and went to the gas station. It then tool fuel as fast as I could deliver it. I don't think in all probability I even needed a new charcoal canister.

This was a tough diagnosis, I hope I saved someone else some time and money

Ladylilu

I've replaced the solenoid, the canister (twice), blown out the lines a few times and just this month replaced the entire fuel tank and lines and another canister. Takes fuel right now but got a small leak Evap code today. Back to the shop. Not sure they checked the filler neck thingy so I'll ask and hope that you saved my truck. Otherwise I have no idea what to do next.

LarryE

What did they do Ladylili?