2005 Tahoe/Fuel filling problem

[Scottydoggs]

canister is likely blown out and clogged up the lines not letting the tank vent as you fill it.

 

[Sam Harris]

Are you sure that it was the purge valve that was changed? It's on the engine. On the other end the vent valve vents the charcoal canister at times, and if it's stuck closed the tank can't vent as fuel is added. When the truck is turned off, the vent valve should be open; it's near the back of the fuel tank. Does your receipt show a part number for said replaced valve? (You likely do not have a vent valve that has been moved; that seems to be on later models.)

Other than that, overfilling the tank can compromise the charcoal canister, and the charcoal can get into the evap lines, blocking venting. I wouldn't base a diagnosis on that but it happens a lot.

You need a Tech 2 and evap knowledge, or a good shop (as @PNW VietVet noted) experienced with these simple systems.

This… so many people “top off” to get their fuel fill to a round number, and have no idea they’re pumping fuel into the charcoal canister, causing a major headache down the road..! This would be my first guess, based on your description, sounds like the venting is plugged. And our GMT800 are not setup identically to the GMT900.. I don’t think the air vent is a common issue getting clogged up. It’s very common, however, for the evap lines to get clogged with gummed up / broken down charcoal, due to having fuel in the charcoal canister.

 

[Tahoe97]

Are you sure that it was the purge valve that was changed? It's on the engine. On the other end the vent valve vents the charcoal canister at times, and if it's stuck closed the tank can't vent as fuel is added. When the truck is turned off, the vent valve should be open; it's near the back of the fuel tank. Does your receipt show a part number for said replaced valve? (You likely do not have a vent valve that has been moved; that seems to be on later models.)

Other than that, overfilling the tank can compromise the charcoal canister, and the charcoal can get into the evap lines, blocking venting. I wouldn't base a diagnosis on that but it happens a lot.

You need a Tech 2 and evap knowledge, or a good shop (as @PNW VietVet noted) experienced with these simple systems.

Great feedback, thanks. Our 05 Tahoe is back @ GMC and they will try to isolate the problem. Part # 12581282 was changed. We also get the "Tighten Fuel Cap" error message which seems unusual as it is tight and was replaced by GMC 1 yr ago on an earlier service. This message only appeared after we started having problems filing the tank.

 

[Tahoe97]

canister is likely blown out and clogged up the lines not letting the tank vent as you fill it.

This has to be the problem! Thanks!

 

[Fless]

The code sets the tighten gas cap msg since the pcm can't sense the evap test being able to draw a vacuum on the tank and the associated evap components. The purge valve (on the engine) you had replaced could have been stuck closed, not allowing the engine vacuum to be applied during the test. It's more likely that something else is either restricting the evap system somewhere, or something is sticking open and venting all the time. Or even that the fuel pressure sensor on the fuel pump is faulty. It's easy enough with a bidirectional scanner like a Tech 2 to test the evap system and determine which component(s) is/are at fault, if one knows how to read the data.

Your fuel filling problem screams blockage somewhere in the system, either a vent valve remaining closed all the time, or plugged charcoal canister or lines. Are you shutting off the truck when fueling?

This is one of several Wells videos that describe how the evap system works, and a bit of diagnosis. If you want to understand more about these simple evap systems I would recommend watching this and some of the other evap videos on the Wells YouTube site.

 

[PNWYukon]

We are now having difficulty actually filling the fuel tank in our 05 Tahoe. The fuel nozzle from the gas station (any gas station) continues to kick off when we have it locked to fill, even on the slowest setting. Even if we manually hold the handle and try to fill after a gallon or so it kicks off, acting like the tank is filled which it clearly is not. Our local GMC dealership changed out the purge valve which after picking it up today did NOT solve the problem. We are also getting an error message on the dash telling us to tighten the fuel cap. This all started about 10 days ago and it now takes forever to fill the tank, 1-2 gallons at a time.

Does anyone have any idea about what might be going on with this?

Thanks,

JHE

On my 2005 Tahoe I started getting the tighten gas cap message and occasionally the gas pumps at Safeway would kick off, but not at ARCO, but at Shell and not at Fred Meyer. I cleared the Gas Cap Code and it came right back.

I spent a few bucks on the easiest things first; Vapor Canister Purge Valve/Solenoid and a new gas cap. Problem Solved.

 

[Tahoe97]

The code sets the tighten gas cap msg since the pcm can't sense the evap test being able to draw a vacuum on the tank and the associated evap components. The purge valve (on the engine) you had replaced could have been stuck closed, not allowing the engine vacuum to be applied during the test. It's more likely that something else is either restricting the evap system somewhere, or something is sticking open and venting all the time. Or even that the fuel pressure sensor on the fuel pump is faulty. It's easy enough with a bidirectional scanner like a Tech 2 to test the evap system and determine which component(s) is/are at fault, if one knows how to read the data.

Your fuel filling problem screams blockage somewhere in the system, either a vent valve remaining closed all the time, or plugged charcoal canister or lines. Are you shutting off the truck when fueling?

This is one of several Wells videos that describe how the evap system works, and a bit of diagnosis. If you want to understand more about these simple evap systems I would recommend watching this and some of the other evap videos on the Wells YouTube site.

yes it does scream blockage. When we picked up the Tahoe after the purge valve was replaced we still say the Tighten Gas Cap message. It is back at GMC today for further diagnosis. I called them and alerted them to the smoking gun likely being a clogged charcoal canister and/or faulty solenoid vent valve. We'll see what they come back with. What ticks me off most is that they sent their tech to put $25 of gas in the Tahoe after they replaced the purge valve and the tech reported no issues putting the gas in which is B.S. because after we picked it up and saw the Tighten Fuel Cap message we went straight to the gas station and the nozzle kept shutting off and wouldn't stay filling.

 

[Fless]

I don't know why they would change the purge valve on the engine for a fuel filling problem; it has nothing to do with the venting during the fill.

 

[Tahoe97]

Turns out the charcoal canister was filled with fuel so it was replaced as well as the valve solenoid. They credited me for the purge valve replacement so all 3 are now new. We'll know if this solved the issue when we fill up next. No more "Tighten Gas Cap" message so at least that is a positive.

 

[Fless]

Be careful in the future to not top off the fuel after the first click or so. Overfilling the tank can saturate the charcoal canister.