Gas cap hissing. Can’t 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]