Got the dreaded slow tank fill

[Bill 1960]

I'm not aware of any check valves in the tank. That is not to say there isn't one, I just have never heard of it or seen one.

I don’t see how a check valve could be used in the tank, how would the vapors travel from the tank to the canister if they did that?

 

[kbuskill]

Uh,.... Where are the vent tubes?? I had my '05 Yukon XL vent system re-done completely because of this problem, but sometimes it still does it..... ( I was at a Shell station last week and it filled up fine)

( So, the filling stops..... sometimes ..... ( Maybe it is the specific station??)

Beats me....

The vent tubes all attach to the charcoal/vapor canister.

One from the tank to the canister.
One from the canister to the purge valve on the intake manifold.
One from the canister to the vent valve solenoid above the spare tire.

Unhook the first one I mentioned from the canister and pressurize the fuel tank with air via the fuel filler neck using a blow gun and a rag to seal around the filler neck at the gas cap. Be careful when doing this as the tank is plastic and you can actually watch it expand when you pressurize it, you don't want to over pressurize it and possibly damage it.

Unhook the second one from the canister and also from the purge valve at the intake and use compressed air to blow through the line from the engine towards the canister.

It helps to have two people that way one of you can operate the blow gun while the other holds a finger or thumb over the open end of the lines where they normally connect to the canister. This helps to build a little pressure up and then when you remove the thumb/finger it allows it to relieve pressure abruptly which helps to expel the pellets.

This method should clear most of the pellets from the lines.

 

[kbuskill]

I don’t see how a check valve could be used in the tank, how would the vapors travel from the tank to the canister if they did that?

Yeah, that is what I was thinking too. I can't say with 100% certainty that GM didn't stick one in somewhere in one of the lines, as there are other lines on the tank that connect the front and rear of the tank and are Y-ed together, but it just seems unlikely.

I will try to look in the factory service manual and see if I can find anything.

 

[kbuskill]

This is all I could find...

I didn't see a check valve mentioned.

 

[09_4WD_YUKON]

Next step before I change the tank is to pressurize the current tank. Here is my logic; gonna disconnect the vent lines 1st to see if the tank will pressurize that way. If so, then something in the tank is plugged. If not, then IDK WTF is going on.

 

[09_4WD_YUKON]

Unhook the first one I mentioned from the canister and pressurize the fuel tank with air via the fuel filler neck using a blow gun and a rag to seal around the filler neck at the gas cap. Be careful when doing this as the tank is plastic and you can actually watch it expand when you pressurize it, you don't want to over pressurize it and possibly damage it..

So, when I do this and the tank does NOT vent then there's the blockage and changing the tank is a possibility.

 

[petethepug]

Subscribed. Thank you for all the documentation. My 09 is doing the same. Here in Cali it’s even worse on the fill ups as the nozzles have vapor recovery that shut off flow.


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[09_4WD_YUKON]

I swear I'm about to burn the mf'er to the ground!!! LOL, not really tho

 

[gooffeyguy]

Subscribed. Thank you for all the documentation. My 09 is doing the same. Here in Cali it’s even worse on the fill ups as the nozzles have vapor recovery that shut off flow.


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We used to have those vapor recovery hoses over the nozzles here since 1987, but got rid of them in 2012 or 2013.

All cars and light trucks built since 2006 have vapor recovery systems built in to capture vapors before they reach the nozzle.

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[09_4WD_YUKON]

I'm done. Nothing works! Tank vents, line from canister to solenoid on engine is clear and still take 1/2 gallon of fuel (different station) and pump shuts off. However, it did take a little more fuel this time and did not backsplash fuel everywhere.

Tried taking vent from tank to canister off, air flowed right thru, no blockage.

So I guess next step is to get this used tank for $25 and see if that works. If not, gotta drop $700 for a new one.

And I did check the solenoid, put power to it and it clicks.f

I'm at a loss. F'ing sucks!!!!

South Louisiana heat and 20 minute fillups will not be a good combo!!!!

 

[gooffeyguy]

What is the line that runs up near the filler tube and has a plastic plug in the end?

I noticed this line when I replaced the air compressor. It is attached to the same mounting point that the compressor intake hose is.

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[kbuskill]

What is the line that runs up near the filler tube and has a plastic plug in the end?

I noticed this line when I replaced the air compressor. It is attached to the same mounting point that the compressor intake hose is.

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That hose comes off of the vent valve that mounts above the spare tire.

 

[kbuskill]

So, when I do this and the tank does NOT vent then there's the blockage and changing the tank is a possibility.

So when you pressurize the tank from the filler neck with air from a blow gun/compressor you get nothing out of any of the lines going to the vapor canister???

Did you see the fuel tank expand the way I described?

 

[exp500]

Gary- I gather that you pressurized tank thru gas cap fwd toward charcoal can with no restrictions. As I see it that only leaves the charcoal can Plugged, if its clear from charcoal can to motor. Me, I would probably try surgery on the can, activated charcoal is cheap and so is stainless screen. At least after surgery I know what it really is even if I have to replace it.

 

[09_4WD_YUKON]

So when you pressurize the tank from the filler neck with air from a blow gun/compressor you get nothing out of any of the lines going to the vapor canister???

Did you see the fuel tank expand the way I described?

Air is coming thru the line that vents the tank to the canister, very little to no restriction.

Could not really see the tank expand. I may have not put enough air into it.

 

[09_4WD_YUKON]

Gary- I gather that you pressurized tank thru gas cap fwd toward charcoal can with no restrictions. As I see it that only leaves the charcoal can Plugged, if its clear from charcoal can to motor. Me, I would probably try surgery on the can, activated charcoal is cheap and so is stainless screen. At least after surgery I know what it really is even if I have to replace it.

I'm sure this does not matter, but the canister is new. I haven't thought about it being plugged tho. I've also thought about unplugging the vent line from the tank to the canister and trying to fill up like that.

 

[kbuskill]

Air is coming thru the line that vents the tank to the canister, very little to no restriction.

Could not really see the tank expand. I may have not put enough air into it.

Did any more pellets come out?

When we did mine it blew pellets out all over the floor. Capping the end of the line with your finger, that goes to the canister, while allowing a little pressure to build up and then releasing it helps to force them out.

 

[kbuskill]

I'm sure this does not matter, but the canister is new. I haven't thought about it being plugged tho. I've also thought about unplugging the vent line from the tank to the canister and trying to fill up like that.

Unplugging the line from the canister and trying to fill up is a good idea. It would definitely help you to narrow down the problem.

Is it possible that something could have gotten dropped down the filler neck?

 

[09_4WD_YUKON]

Did any more pellets come out?

When we did mine it blew pellets out all over the floor. Capping the end of the line with your finger, that goes to the canister, while allowing a little pressure to build up and then releasing it helps to force them out.

No pellets anywhere, not even in the line going to the engine. Really why I am stumped now. So, the tank has to be plugged somewhere.

 

[09_4WD_YUKON]

Unplugging the line from the canister and trying to fill up is a good idea. It would definitely help you to narrow down the problem.

Is it possible that something could have gotten dropped down the filler neck?

I really don't think so. I was able to fill it very, very slowly yesterday. Would take a couple of gallons before it clicked off.