How to know if PO tanked the charcoal canister (1 Viewer)

[AtoyotA]

A couple weeks ago I was driving around with the windows down and I noticed some terrible gas fumes everywhere I went. Being that it wasn't location based, I deduced it was coming from my 100 so I pulled over and sniffed around my truck and sure enough there was a nose-burning stench of gas around the fuel tank (specifically in the driver rear wheel well). Now I was on half a tank and hadn't filled up lately so I found this concerning. I unscrewed the gas cap and was blasted with more gas fumes than I've ever experienced when refueling. Weird. I went ahead and replaced the gas cap with a new OEM gas cap just in case and prayed that was the culprit.

Fast-forward to today: I went to fill up and the pump just immediately auto shut off - no matter how much finesse, it would shut off. I noticed that there were alot of gas fumes coming out of my tank and when I screwed the cap back on and then unscrewed it enough to release fumes, it hissed for over 3 minutes until I got bored and left.

Never had this happen before so I have no frame of reference. What could be causing this? My only thought is the PO topped it off a ton and clogged the charcoal canister, but idk what the internals of a canister look like so idk if that would cause this. Also it seems to only happen when it's hot outside. Clearly the tank is not breathing properly, but that's as far as I've gotten. Help!

 

[CorporalClegg]

A couple weeks ago I was driving around with the windows down and I noticed some terrible gas fumes everywhere I went. Being that it wasn't location based, I deduced it was coming from my 100 so I pulled over and sniffed around my truck and sure enough there was a nose-burning stench of gas around the fuel tank (specifically in the driver rear wheel well). Now I was on half a tank and hadn't filled up lately so I found this concerning. I unscrewed the gas cap and was blasted with more gas fumes than I've ever experienced when refueling. Weird. I went ahead and replaced the gas cap with a new OEM gas cap just in case and prayed that was the culprit.

Fast-forward to today: I went to fill up and the pump just immediately auto shut off - no matter how much finesse, it would shut off. I noticed that there were alot of gas fumes coming out of my tank and when I screwed the cap back on and then unscrewed it enough to release fumes, it hissed for over 3 minutes until I got bored and left.

Never had this happen before so I have no frame of reference. What could be causing this? My only thought is the PO topped it off a ton and clogged the charcoal canister, but idk what the internals of a canister look like so idk if that would cause this. Also it seems to only happen when it's hot outside. Clearly the tank is not breathing properly, but that's as far as I've gotten. Help!

You need to check the canister vent valve, it is what allows the tank to breath through the canister to atmosphere. If it's stuck closed you'll not be able to fuel up the vehicle.

If you're wondering if the canister has been fuel soaked the best way is to monitor fuel trims or o2 sensor for rich condition during a purge event. You should get a cel of either has failed. Though a stuck vent valve dtc can take several days of failure 3 failed tests that take several hours to run after the engine has been shut off for x amount of time, usually 4 to 5 hours.

 

[AtoyotA]

You need to check the canister vent valve, it is what allows the tank to breath through the canister to atmosphere. If it's stuck closed you'll not be able to fuel up the vehicle.

If you're wondering if the canister has been fuel soaked the best way is to monitor fuel trims or o2 sensor for rich condition during a purge event. You should get a cel of either has failed. Though a stuck vent valve dtc can take several days of failure 3 failed tests that take several hours to run after the engine has been shut off for x amount of time, usually 4 to 5 hours.

Ok hopefully it's just a valve and not the canister itself. What is a purge event?

 

[Coin]

I’d love more info on this thread. I get a gas smell sometimes, but no hissing at the fuel cap and can fill up fine. My garage never smells, so I don’t believe it’s a leak.

It also seems like something is holding back my engine. I’m wondering if it’s evap or a vacuum line issue.

 

[Mike NXP]

You need to check the canister vent valve, it is what allows the tank to breath through the canister to atmosphere. If it's stuck closed you'll not be able to fuel up the vehicle.

If you're wondering if the canister has been fuel soaked the best way is to monitor fuel trims or o2 sensor for rich condition during a purge event. You should get a cel of either has failed. Though a stuck vent valve dtc can take several days of failure 3 failed tests that take several hours to run after the engine has been shut off for x amount of time, usually 4 to 5 hours.

You could disconnect the canister all together and eliminate that as an option.

How hot is it in your area?

Do you monitor engine temps? If so, what are your ECTs?

This is a known problem if it relates to heat. There are a lot of threads on it

 

[Live to Ski]

w/r to "shorting out the canister", wouldn't this throw codes?

A distant (un) related topic: when the egr valve on my 60 froze (impacting idle), I shorted that out to remove that action from the emmissions system (plugged a couple vacuum lines). Kinda sucks driving around w/o those things working.....think CA smog days back in the 70's/early 80's. (un)luckly, the 60 rests peacefully in the garage.

 

[fooldall1]

Can someone explain the testing procedures for the simple fixes for this issue? I am pretty ok wrenching this myself but noticed the hissing gas cap and the strong fuel smell. I hate to ask what seems like an elementary question, but the fuel eval system is nothing I've tried to fix on my Hundy before.

TIA.