Gas cap hissing. Can barely pump gas.

[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 dont think it does it when its off, it seems like the pressure goes somewhere..... maybe just slowly? it hisses when its running.

 

[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.

did this work for you

 

[iboughtatahoe23]

very curious about trying that

 

[tuckerrnr1]

Yes, with the new canister and canister vent valve, purging in the described manor worked for me. A shop vac with the hose on the exhaust side might work as well. I applied air pressure for at least ten minutes until I saw no more charcoal coming out.

 

[iboughtatahoe23]

Yes, with the new canister and canister vent valve, purging in the described manor worked for me. A shop vac with the hose on the exhaust side might work as well. I applied air pressure for at least ten minutes until I saw no more charcoal coming out.

All I have is an air compressor

 

[iboughtatahoe23]

Also my long term fuel trims are reading -10 and -12 in both banks. Am I running lean? Could the clogged lines or bad purge valve vent solenoid cause this

 

[iboughtatahoe23]

Yes, with the new canister and canister vent valve, purging in the described manor worked for me. A shop vac with the hose on the exhaust side might work as well. I applied air pressure for at least ten minutes until I saw no more charcoal coming out.

waht u mean by hose on the exhaust side

edit; read this wrong i understand now, you mean using the blowing function on teh vaccum

 

[tuckerrnr1]

With all the sixth graders on here I was reluctant to say "Put it on suck instead of blow".

 

[iboughtatahoe23]

With all the sixth graders on here I was reluctant to say "Put it on suck instead of blow".

U mean blow instead of suck

 

[tuckerrnr1]

 

[Fless]

Also my long term fuel trims are reading -10 and -12 in both banks. Am I running lean? Could the clogged lines or bad purge valve vent solenoid cause this

Running rich. The PCM is taking away fuel (negative trims) because it's being told there's too much fuel by the O2 sensors. A bad purge valve can cause this, among other things, as can fuel contamination in the oil.

 

[iboughtatahoe23]

Running rich. The PCM is taking away fuel (negative trims) because it's being told there's too much fuel by the O2 sensors. A bad purge valve can cause this, among other things, as can fuel contamination in the oil.

Just opened my hood and my coolant is very low for some reason as well … View attachment 450627

 

[iboughtatahoe23]

Yes, with the new canister and canister vent valve, purging in the described manor worked for me. A shop vac with the hose on the exhaust side might work as well. I applied air pressure for at least ten minutes until I saw no more charcoal coming out.

I tried doing that; blowing down the filler neck with a air compressor and the little slot above the filler neck, with the charcoal canister off nothing came out of the EVAP lines even when I set a slab of cardboard under it it looks like just some water came out a few drops

 

[iboughtatahoe23]

Wondering if anyone knows what the hose going from the vent valve on the back above the spare, to the filler neck at the end of it by the filler neck there is a square deal that feels like a small filter maybe 3 inches wide 3 inches long. And then that hose goes back down to the vent valve. The issue is is there’s no quick connect/disconnect on the vent valve side to disconnect that hose so I’m having trouble getting the vent valve out.

 

[iboughtatahoe23]

 

[Fless]

That's the remote filter for the vent valve. It's usually full of dirt and blocked when certain evap issues happen.

 

[donjetman]

@iboughtatahoe23 part of the vapor cannister vent system
https://www.summitracing.com/parts/...1458812157440&utm_content=GSAPI+5d652b95b0b8b

 

[petethepug]

Based on time and milage there’s four things due on the fuel system.

* Replace charcoal canister. Check!
* Replace Vapor canister purge solenoid valve @ filler neck.
* Replace Vapor canister purge valve on engine block.
* Replace fuel pump / sender with OEM unit.

Then, blow out all the lines when the tank is out and swab’d clean. It’s got to be done systematically to get you back to uninterrupted fill ups.

Post #49 has part # Ref for the 6.2L likely the same for the 09-14 5.3L

'Upgraded from a 2008 Denali to a 2009 Eski'
https://www.tahoeyukonforum.com/thr...008-denali-to-a-2009-eski.117499/post-1688395

 

[iboughtatahoe23]

That's the remote filter for the vent valve. It's usually full of dirt and blocked when certain evap issues happen.

View attachment 450763

Just got it off. Lots of dust and dirt in that filter.

 

[iboughtatahoe23]

Based on time and milage there’s four things due on the fuel system.

* Replace charcoal canister. Check!
* Replace Vapor canister purge solenoid valve @ filler neck.
* Replace Vapor canister purge valve on engine block.
* Replace fuel pump / sender with OEM unit.

Then, blow out all the lines when the tank is out and swab’d clean. It’s got to be done systematically to get you back to uninterrupted fill ups.

Post #49 has part # Ref for the 6.2L likely the same for the 09-14 5.3L

'Upgraded from a 2008 Denali to a 2009 Eski'
https://www.tahoeyukonforum.com/thr...008-denali-to-a-2009-eski.117499/post-1688395

I replaced the charcoal canister, purge solenoid by the fuel rail, and I’m currently working on cleaning the vent valve right now… you think the fuel pump?

And what’s the vapor canister by the filler neck? Did I miss that.