2005 Tahoe gas filling / purge canister - clearing lines of carbon

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Fless

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My '04 FF tank will come down without removing any of the evap lines from the clips on the tank, just disconnecting two connectors (canister and vent valve). Only the fuel lines need to be disconnected and snapped out of the plastic clips (on the left in the pic below, which is the driver's side). Everything else stays on.

It's easier to leave the fuel lines on the truck, just disconnecting from the pump, since the fuel line connections at the front of the tank are virtually impossible to access and undo -- ok, it can be done with some finagling of the tank in the process of removal, but why take on the hassle? They're well exposed after dropping the tank, in the rare case that any work is needed on them.

2021-08-15 Fuel Tank.jpg
 
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tennfire

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Thanks for the replies so far.
Other than one place where I saw a comment on a Youtube, anyone have thoughts about disconnecting the lines, leaving the tank in place, and pressurizing the tank with a rag and air hose - low but gentle pressure?
 

iamdub

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Thanks for the replies so far.
Other than one place where I saw a comment on a Youtube, anyone have thoughts about disconnecting the lines, leaving the tank in place, and pressurizing the tank with a rag and air hose - low but gentle pressure?

Through the pump, etc.? Nah.

Have you disconnected any lines yet to see if you even have loose pellets? It could just be a failed vent valve.
 

Blk00ss

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I have a good amount of experience with this issue. We recently delt with it on my son's '05 Tahoe with 171K on it. At about 150K we started having fueling issues. Slow fueling, backflow of gas everywhere etc. I replaced the typical stuff with no change. Started seeing people talk about carbon build up not allowing the tank to basically breath. So I started with disconnecting the two lines (white clips) going to the evap canister. As soon as they came unhooked, pieces of carbon fell in my face. I sucked out from those lines what I could with my shop vac. No change. Tried to jiggle the lines best I could with tank still in truck and could get a little more carbon out, but not enough. I really didn't wanna remove the tank, so I tried something else. I took a little oil funnel. I cut the tapered end just to make the hole a bit bigger. I put it in the the fill hole and pushed it in tight. I then took the exhaust side of my shop vac and stick it the funnel....carbon blew out of those disconnected lines everywhere. You wanna do this in pulses like on off. You will actully see the tank flexing as you're doing this. To me it seemed to help almost like "burping" the fuel tank and lines.

It did not fix the issue right away. I would blow out what I could, and we would drive for a week or so with the lines disconnected still from the evap canister (this won't hurt the vehicle, but it may throw a light). Blow out again the next weekend. I guess driving it around would loosen more and more carbon. Finally after a few weeks of doing this, I couldn't get anymore to blow out. And now, she takes fuel better than she ever has and we've owned it since almost new.
 

mountie

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I read this thread.... Boy,... I need a 'line' road map...
I had replaced my Canister Purge Solenoid, Canister Vent Valve, Fuel Vapor Canister, back in 2020.
Still having fill-up issues...... That canister next to the battery.... should that be replaced?

I need to learn where those vent lines are under the hood......
 

Blk00ss

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Thanks for the replies so far.
Other than one place where I saw a comment on a Youtube, anyone have thoughts about disconnecting the lines, leaving the tank in place, and pressurizing the tank with a rag and air hose - low but gentle pressure?
See my below post. It worked on mine and its worked on others. Some use a leaf blower. However, "gentle" pressure probably won't do much.
 

Blk00ss

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Letting the tank down is easy and gets it all out in one day, especially if you’re already down there disconnecting lines., there’s not much to else to it
Regardless, the method I used and others have used as well was pretty simple, straight forward and not messy. The filling issue got better every time and after a few passes, it was 100%
 

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