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Discussion Starter #1 (Edited)
Ok my guess is that someone out there has experienced this. My red gt convert starts and runs perfect when fuel tank is half full or lower. Twice now, go to the fuel station and fill the tank with gas and within seconds the engine just dies.

Boomer, DX, 1 of (aka) mark or anyone else?

I eventually can get back to the house butbut for how long?



Thanks
Convertme

Ps. Look for my latest update under dxg6 thread regarding gas struts that are too long
 

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So what happens when it dies? Does it restart with no trouble? Does it keep dying until you use half a tank? How often does it die?
 

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Ok my guess is that someone out there has experienced this. My red gt convert starts and runs perfect when fuel tank is half full or lower. Twice now, go to the fuel station and fill the tank with gas and within seconds the engine just dies.

Boomer, DX, 1 of (aka) mark or anyone else?

I eventually can get back to the house butbut for how long?



Thanks
Convertme

Ps. Look for my latest update under dxg6 thread regarding gas struts that are too long
As I recall, this is usually due to a clogged filter on the vapor recovery system, called the vapor canister. https://www.gmpartsdirect.com/oem-parts/gm-vapor-canister-10376010/?c=Zz1lbWlzc2lvbi1zeXN0ZW0mcz1lbWlzc2lvbi1jb21wb25lbnRzJmk9Q1AwNDM2NTUmcj03JmE9cG9udGlhYyZvPWc2Jnk9MjAwNyZ0PWd0JmU9My01bC12Ni1nYXM=

You will need to verify that. Not sure the details how, tho.

What I've read is that typically it gets clogged by topping off the tank when the car is filled up. Fuels gets into the vapor line and goes into the carbon filter in the canister.

I have never had to fix one on my G6 (or any other car), so I can't shed a lot of light on it. But that's what I've read.

Doug

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Discussion Starter #4
So what happens when it dies? Does it restart with no trouble? Does it keep dying until you use half a tank? How often does it die?
It Has restarted every time so far. It may stutter then die or may just die. Don't know the number of times.
It did seem to get betterasit got closer to the 1/2, not necessarily is it 1/2either.
Totally random I would say.
 

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Discussion Starter #5
As I recall, this is usually due to a clogged filter on the vapor recovery system, called the vapor canister. https://www.gmpartsdirect.com/oem-parts/gm-vapor-canister-10376010/?c=Zz1lbWlzc2lvbi1zeXN0ZW0mcz1lbWlzc2lvbi1jb21wb25lbnRzJmk9Q1AwNDM2NTUmcj03JmE9cG9udGlhYyZvPWc2Jnk9MjAwNyZ0PWd0JmU9My01bC12Ni1nYXM=

You will need to verify that. Not sure the details how, tho.

What I've read is that typically it gets clogged by topping off the tank when the car is filled up. Fuels gets into the vapor line and goes into the carbon filter in the canister.

I have never had to fix one on my G6 (or any other car), so I can't shed a lot of light on it. But that's what I've read.

Doug

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I have a parts car that runs good. Would you consider a used one or go completely new? And why run good on the bottom 1/2 vs. the top half.
 

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I have a parts car that runs good. Would you consider a used one or go completely new? And why run good on the bottom 1/2 vs. the top half.
I would definitely try the used one first. I think the canister is mounted inside the quarter panel near the filler neck. So swapping it out should require jacking the car, removing the wheel, partially removing the fender liner, then removing the canister. For a 150 bucks, I'll burn an hour or two doing that.

As for why it works half full but not all the way, my half baked theory is that the vapor recovery system tries to move some vapor thru the system at engine crank, and, if the tank is full and the canister clogged, the system chokes on it thereby somehow preventing the engine from firing. Whereas, with the tank half full, there's enough elasticity (ie, compressible air volume) in the system to squeeze the "burp" of vapor into the tank without choking things on the other end.

As I understand it, using the solenoid actuated valves at each end of the car, the system attempts to recycle vapors from the engine end of the fuel system back to the tank rather than releasing them into the atmosphere, like we did in the old days :)

Beyond that, I don't know much about vapor recovery other than to not top off the tank after the pump stops like Dad did :) (And like I did for the first 30 years of driving ;) )

Doug

[Edit]Thinking about this some more, there's a small hose that connects to the filler neck. I think, when the tank is topped off, that hose gets gasoline in it, which does indeed choke the system when it attempts to burp itself. After that hose clears itself (however that works) the hard-start problem goes away.

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As I understand it, using the solenoid actuated valves at each end of the car, the system attempts to recycle vapors from the engine end of the fuel system back to the tank rather than releasing them into the atmosphere, like we did in the old days :)
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There are two separate things.
One, some cars used to have fuel return lines. They kept fuel moving, anything pumped up and not used at the injectors went back to the tank. This was a recirculation system to keep fuel from boiling at the engine end. I don't believe anybody does that anymore for many years now. But I don't see how it could stall the engine when the tank is full, even if faulty.
Two, the vapor recovery system. It soaks up into the canister any fuel vapor in the tank. Then under certain engine conditions (based on load, etc.) it releases the vapor into the intake, to be burned with the rest of the fuel. Again, I don't see how a malfunction of this system would be different with a full tank.

But just because I don't see it, it doesn't mean it can't happen :)
 

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Discussion Starter #8 (Edited)
There are two separate things.
One, some cars used to have fuel return lines. They kept fuel moving, anything pumped up and not used at the injectors went back to the tank. This was a recirculation system to keep fuel from boiling at the engine end. I don't believe anybody does that anymore for many years now. But I don't see how it could stall the engine when the tank is full, even if faulty.
Two, the vapor recovery system. It soaks up into the canister any fuel vapor in the tank. Then under certain engine conditions (based on load, etc.) it releases the vapor into the intake, to be burned with the rest of the fuel. Again, I don't see how a malfunction of this system would be different with a full tank.

But just because I don't see it, it doesn't mean it can't happen :)
I feel that "red 3.9" seems to have plenty of moisture in muffler while the car with the 3.5 liter does not have near that amount. Does this new information help anyone at all??
 

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Not really. Water vapor is a product of combustion. When the pipes are cold, that vapor condenses and you sometimes see it come out of the tailpipe in liquid form. As the pipes heat up, no more condensation and any previous condensate boils off.
Not sure how you determined "moisture" in the 2 cars. There can only be liquid water when the exhaust is cold. There can be differences in how long each takes to get hot, maybe one is a dual exhaust and one is not, etc. But 2 engines generating the same hp will generate the same amount of water vapor and I don't see how a fault can generate more water.
 

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Discussion Starter #10
Because I have a few extra parts lying around, I thought well let's try the MAF sensor but that made no difference. Take that one off the list.
The vapor canister is out of town. I am kind of concerned that it might be the ECU but I will pick up the one from the car when I get vapor canister. Can anyone tell me if it needs to be programmed to the car??
Thanks
Convertme
 

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Discussion Starter #11
As I recall, this is usually due to a clogged filter on the vapor recovery system, called the vapor canister. https://www.gmpartsdirect.com/oem-parts/gm-vapor-canister-10376010/?c=Zz1lbWlzc2lvbi1zeXN0ZW0mcz1lbWlzc2lvbi1jb21wb25lbnRzJmk9Q1AwNDM2NTUmcj03JmE9cG9udGlhYyZvPWc2Jnk9MjAwNyZ0PWd0JmU9My01bC12Ni1nYXM=

You will need to verify that. Not sure the details how, tho.

What I've read is that typically it gets clogged by topping off the tank when the car is filled up. Fuels gets into the vapor line and goes into the carbon filter in the canister.

I have never had to fix one on my G6 (or any other car), so I can't shed a lot of light on it. But that's what I've read.

Doug

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I did manage to get out to my parts car today. So along the way, I drive right past the door step of a gm dealer. I decide to stop to see if he can help short of putting the car on a computer to diagnose the issue. i couldn't because it will drive that far.
He strongly recommended trying the purge valve first. I come home with, purge valve,vapor canister and filter and the ecm.
Purge valve did not fix the issue though.
Next will be to try the cannister.
Doug,,, when I got home I looked closer at the canister and filter from the parts car. There was a lot more dust and dirt in the hose and canister than I would ever have imagined. Maybe that is my issue. Although both cars come from relatively the same area, maybe they were driven mostly on gravel or creating extreme dust conditions.
Is it possible or prudent to attempt cleaning the filter first?
Slow process but I will get there.
Thank you,
Convertme
 

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Is it possible or prudent to attempt cleaning the filter first?
I wouldn't get it wet. If you have a small vacuum attachment, you might try to remove some of the dust with that. Some times, an air hose is handy for blasting dust off things. It would be useful to blow out the hoses, too.

HTH.

Doug

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My bet is the Vapor Canister Vent Valve Usually found in back near the fuel tank or in one of the rear wheel arch areas. Had to work with same type valve recently on my Dad's 07 Buick LaCrosse (I hate that car).
But more importantly to your problem...From what I know of these GM computerized caliginous clanking collections of - - - -(wiz. of OZ)
you should have been having a CEL illuminating and codes for the problem.

EDIT: SORRY folks, but I'm NOT a full on convert of GM products yet. I go MOPAR a LONG way back and before that was a VW man!
 

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Discussion Starter #14 (Edited)
My bet is the Vapor Canister Vent Valve Usually found in back near the fuel tank or in one of the rear wheel arch areas. Had to work with same type valve recently on my Dad's 07 Buick LaCrosse (I hate that car).
But more importantly to your problem...From what I know of these GM computerized caliginous clanking collections of - - - -(wiz. of OZ)
you should have been having a CEL illuminating and codes for the problem.

EDIT: SORRY folks, but I'm NOT a full on convert of GM products yet. I go MOPAR a LONG way back and before that was a VW man!
I had hoped of resolving this once and for all today but hardly got to the plate before other things come up.
Maybe tomorrow. I am thinking that you are right though. It seems like I am getting more vacuum in the fuel tank since I replaced the purge valve not sure if this changes my mind or anything for that matter. From what I read, the canister valve is a well documented failure part.
On to the matter of gm..... The general has been noted for placing some parts in hard to get at locations and the canister on these cars are no exception!
 

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Discussion Starter #15 (Edited)
I had hoped of resolving this once and for all today but hardly got to the plate before other things come up.
Maybe tomorrow. I am thinking that you are right though. It seems like I am getting more vacuum in the fuel tank since I replaced the purge valve not sure if this changes my mind or anything for that matter. From what I read, the canister valve is a well documented failure part.
On to the matter of gm..... The general has been noted for placing some parts in hard to get at locations and the canister on these cars are no exception!
Went to the gm dealer today.
There is a vent in the fuel pump that went haywire causing fuel to get into the vapor canister and the charcoal filter and causing me the issues as described earlier in this thread.
Had all the parts but decided to go new with an aftermarket fuel pump by Carter. The rest will be my own used parts. Plus labor and tax on any new parts and of course those silly shop materials.

Convertme...
if I want to play I have to pay
 

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Glad you found the cause! So you got the job done already?

Not familiar with the GM fuel pump assemblies...as I stated I'm a MOPAR man! Our G6 is the Wife's wanted ride!
 

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Discussion Starter #17
Went to the gm dealer today.
There is a vent in the fuel pump that went haywire causing fuel to get into the vapor canister and the charcoal filter and causing me the issues as described earlier in this thread.
Had all the parts but decided to go new with an aftermarket fuel pump by Carter. The rest will be my own used parts. Plus labor and tax on any new parts and of course those silly shop materials.

Convertme...
if I want to play I have to pay
Thanks for all of your input everyone!
 

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Discussion Starter #18
Glad you found the cause! So you got the job done already?

Not familiar with the GM fuel pump assemblies...as I stated I'm a MOPAR man! Our G6 is the Wife's wanted ride!
Called Thursday
They got the car in Friday
Picked it up Saturday at 1:30

Can't get much better than that....but I think I got a little lucky. The farmers are all busy farming in and around the small community where this dealer located.
I will take it though, I did drive by several city dealers just because of the small town feel that I have always had and enjoyed.
Thanks again.
 
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