Gas cap hissing. Can barely pump gas.

[iboughtatahoe23]

2014 Tahoe Lt 178k

Changed charcoal canister. And now it’s worse. Don’t know how pellets would have gotten in the lines if I took the hoses off before the canister. Any way. This thing clicks off every few dollars and hisses when I take off the cap. I have to trickle it or use a funnel.

Some youtube videos below:
1) Gas cap hiss
2) Pump clicking off

 

[PPV_2018]

Sounds to me like possible fuel vapor issue? Did you purge the lines out when you took them off to replace the charcoal canister

Had a similar issue on a different car where the evap purge solenoid failed choked the fuel system.

 

[Fless]

If the ignition is in the off position (meaning no power to the evap system) either the canister vent valve is not opening or the evap system is somehow plugged. The system shouldn't hold pressure like that with the ignition off.

Here's some of the back story: https://www.tahoeyukonforum.com/threads/charcoal-canister.152136/#post-1935228

 

[Joseph Garcia]

Hopefully, you remove the gas pump at the first click, when filling your tank (prior to this issue). Most canister/pellet issues arise when folks try to top off their gas tanks with successive gas pump clicks after the first one.

 

[iboughtatahoe23]

Hopefully, you remove the gas pump at the first click, when filling your tank (prior to this issue). Most canister/pellet issues arise when folks try to top off their gas tanks with successive gas pump clicks after the first one.

There has been times where I got frustrated and have done this but nine times out of 10 when it clicks off, I’ll let it go back down and then repeat

 

[iboughtatahoe23]

If the ignition is in the off position (meaning no power to the evap system) either the canister vent valve is not opening or the evap system is somehow plugged. The system shouldn't hold pressure like that with the ignition off.

Here's some of the back story: https://www.tahoeyukonforum.com/threads/charcoal-canister.152136/#post-1935228

I noticed it only hisses when the vehicle is on, when I’m filling out the pump and it doesn’t matter if the vehicle is on or off it always clicks off after a few bucks.

 

[iboughtatahoe23]

Sounds to me like possible fuel vapor issue? Did you purge the lines out when you took them off to replace the charcoal canister

Had a similar issue on a different car where the evap purge solenoid failed choked the fuel system.

Yeah, I can’t figure it out and it’s starting to look like the only option is going to be dropping the tank and blowing the lines out which I really don’t wanna do so I’m gonna take it in

Like I said, no idea how the pellets went down the tubes if I took the tubes off before

 

[tuckerrnr1]

When I replaced my canister, while the lines were still disconnected, I blew air into the tank from the filler neck to clean out the lines. I just used an air nozzle and a rag to seal the filler tube. Quite a bit of charcoal came out without having to drop the tank.

 

[Fless]

It's not whether or not the canister was disconnected, the canister can dump charcoal pellets into the lines any time it gets internally compromised. It's probably been leaking them out for a while.

I can't tell -- when it's hissing is it blowing out fumes or sucking in air?

 

[iboughtatahoe23]

It's not whether or not the canister was disconnected, the canister can dump charcoal pellets into the lines any time it gets internally compromised. It's probably been leaking them out for a while.

I can't tell -- when it's hissing is it blowing out fumes or sucking in air?

I believe it is sucking air in. Like the tank is depressurized.

 

[iboughtatahoe23]

When I replaced my canister, while the lines were still disconnected, I blew air into the tank from the filler neck to clean out the lines. I just used an air nozzle and a rag to seal the filler tube. Quite a bit of charcoal came out without having to drop the tank.

Good idea man. Did you do this on a near empty tank?

 

[OR VietVet]

Mine does not do it but it did at one time, I replaced everything and is fixed. Not gonna mess around and piece by piece it. I have gotten in to the habit with all my vehicles and anyone else's I may be putting gas in, and I never stick the nozzle all the way in and I never pump it on the fastest step/click.

 

[tuckerrnr1]

Good idea man. Did you do this on a near empty tank?

No, at least half a tank or more to take up volume in the tank requiring less air.

 

[iboughtatahoe23]

No, at least half a tank or more to take up volume in the tank requiring less air.

OK, I’m going to try this as well as replacing the purge valve solenoid

 

[iboughtatahoe23]

Mine does not do it but it did at one time, I replaced everything and is fixed. Not gonna mess around and piece by piece it. I have gotten in to the habit with all my vehicles and anyone else's I may be putting gas in, and I never stick the nozzle all the way in and I never pump it on the fastest step/click.

Lesson learned. Hopefully get this taken care of

 

[newton4mark]

2014 Tahoe Lt 178k

Changed charcoal canister. And now it’s worse. Don’t know how pellets would have gotten in the lines if I took the hoses off before the canister. Any way. This thing clicks off every few dollars and hisses when I take off the cap. I have to trickle it or use a funnel.

Some youtube videos below:
1) Gas cap hiss
2) Pump clicking off

Had this same issue
Changes all three parts on the evap system and still couldn’t fill up
Dropped the tank and unhooked all the lines and blew them out with compressed air - took a ton of passes
Loaded with charcoal bits
Put it back together and good as new
Nonissue now filling up
I would bet money your lines are clogged

When I took the original canister off
A bunch of charcoal bits fell out
So they got sucked into the lines
It’s pretty common I gues
And a real pain in the ass

 

[iboughtatahoe23]

Had this same issue
Changes all three parts on the evap system and still couldn’t fill up
Dropped the tank and unhooked all the lines and blew them out with compressed air - took a ton of passes
Loaded with charcoal bits
Put it back together and good as new
Nonissue now filling up
I would bet money your lines are clogged

When I took the original canister off
A bunch of charcoal bits fell out
So they got sucked into the lines
It’s pretty common I gues
And a real pain in the ass

Do you really HAVE to drop the tank

 

[solli5pack]

Do you have a scanner? A seal and purge test will tell you exactly what's going on.

 

[iboughtatahoe23]

Do you have a scanner? A seal and purge test will tell you exactly what's going on.

I think when I tried the evap test on the scanner it wouldn’t do it for some reason idk why

 

[iboughtatahoe23]

The only modules I’m able to test are ABS and OBDII